Thanks for the details. Could you please check followings:

• open the log of nginx.access.log

tail -f /opt/zextras/log/nginx.access.log

• While keeping the mentioned log open, try previewing any file and see the logs.

Thanks

Carbonio Release 24.12.1
  UNIT                                               LOAD   ACTIVE SUB     DESCRIPTION

  carbonio-clamav-sidecar.service                    loaded active running Carbonio clamav sidecar proxy
  carbonio-clamav-signature-provider-sidecar.service loaded active running NGINX Carbonio ClamAV signature provider sidecar
  carbonio-docs-connector-sidecar.service            loaded active running Carbonio docs connector sidecar proxy
  carbonio-docs-connector.service                    loaded active running Carbonio docs connector daemon
  carbonio-docs-editor-sidecar.service               loaded active running Carbonio Docs server sidecar proxy
  carbonio-docs-editor.service                       loaded active running Carbonio Docs Server
  carbonio-files-db-sidecar.service                  loaded active running Carbonio Files database sidecar
  carbonio-files-sidecar.service                     loaded active running Carbonio Files sidecar proxy
  carbonio-files.service                             loaded active running Carbonio Files daemon
  carbonio-mailbox-admin-sidecar.service             loaded active running Carbonio Mailbox Admin proxy sidecar
  carbonio-mailbox-nslookup-sidecar.service          loaded active running Carbonio Mailbox NSLookup proxy sidecar
  carbonio-mailbox-sidecar.service                   loaded active running Mailbox carbonio proxy sidecar
  carbonio-message-broker-sidecar.service            loaded active running Carbonio message broker sidecar proxy
  carbonio-message-broker.service                    loaded active running Carbonio message broker daemon
  carbonio-message-dispatcher-auth-sidecar.service   loaded active running Carbonio Message Dispatcher auth sidecar proxy
  carbonio-message-dispatcher-auth.service           loaded active running Carbonio Message Dispatcher auth daemon
  carbonio-message-dispatcher-db-sidecar.service     loaded active running Carbonio Message Dispatcher database sidecar
  carbonio-message-dispatcher-http-sidecar.service   loaded active running Carbonio Message Dispatcher HTTP sidecar proxy
  carbonio-message-dispatcher-xmpp-sidecar.service   loaded active running Carbonio Message Dispatcher XMPP sidecar proxy
  carbonio-message-dispatcher.service                loaded active running Carbonio Message Dispatcher daemon
  carbonio-mta-sidecar.service                       loaded active running Carbonio mta sidecar proxy
  carbonio-preview-sidecar.service                   loaded active running Carbonio Preview sidecar proxy
  carbonio-preview.service                           loaded active running Carbonio Preview daemon
  carbonio-prometheus-consul-exporter.service        loaded active running Carbonio Prometheus Consul exporter
  carbonio-prometheus-mysqld-exporter.service        loaded active running Carbonio Prometheus MySQL exporter
  carbonio-prometheus-nginx-exporter.service         loaded active running Carbonio Prometheus NGINX exporter
  carbonio-prometheus-node-exporter.service          loaded active running Carbonio Prometheus Node Exporter
  carbonio-prometheus-openldap-exporter.service      loaded active running Carbonio Prometheus OpenLDAP exporter
  carbonio-proxy-sidecar.service                     loaded active running NGINX carbonio proxy sidecar
  carbonio-storages-sidecar.service                  loaded active running Storages-CE sidecar proxy
  carbonio-storages.service                          loaded active running Carbonio Storages-CE daemon
  carbonio-tasks-db-sidecar.service                  loaded active running Carbonio Tasks database sidecar
  carbonio-tasks-sidecar.service                     loaded active running Carbonio Tasks sidecar proxy
  carbonio-tasks.service                             loaded active running Carbonio Tasks daemon
  carbonio-user-management-sidecar.service           loaded active running Carbonio User Management sidecar proxy
  carbonio-user-management.service                   loaded active running Carbonio User Management daemon
  carbonio-videoserver-sidecar.service               loaded active running Carbonio Videoserver sidecar proxy
  carbonio-videoserver.service                       loaded active running Zextras Videoserver
  carbonio-ws-collaboration-db-sidecar.service       loaded active running Carbonio Workstream Collaboration database sidecar
  carbonio-ws-collaboration-sidecar.service          loaded active running Carbonio Workstream Collaboration sidecar proxy
  carbonio-ws-collaboration.service                  loaded active running Carbonio Workstream Collaboration daemon
  carbonio.service                                   loaded active exited  LSB: Carbonio Services

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

42 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

Could you please share the output of following:

su - zextras -c "zmcontrol -v" && systemctl list-units carbonio*

https://docs.zextras.com/carbonio-ce/html/architecture/components/component-docs.html 

Checkout also your /var/log/syslog and verify that all service are up&run

carbonio-preview-ce - installed, service - working

download files - working, but no preview in carbonio mail and carbonio files, after clicking to files it open in new windows or downloading.