Shared calendars on mobile not appear

Hi,

I try to enable shared calendars sync on a mobile.
I follow this : https://wiki.zextras.com/wiki/ZxMobile_and_Shared_Folders

- I use zextra 2.6.7 on zimbra 8.8.9.
- I deployed Zextras Client Zimlet
- I enabled the Zextras client zimlet for the account via the COS.
- I created a shared calendar with the right "Manager"
- On the shared calendar I check "Enable synchronization for this folder"

However, it doesn't appear on the mobile (Huawei p10 lite with default agenda app).

What did I miss ?