• You need to install the Collabora Plugin in your File Sync and Share solution (see below for more information).
• Then you can give https://FQDN_OF_THIS_SERVER without a port number as the WOPI URL in your preferred File Sync and Share solution.
• Please make sure the File Sync solution has access to the Root CA of the UCS domain (see below for more detailed information).
• Make sure your browser can resolve the FQDN of the File Sync and Collabora Online server.
• Accept the certificate of the Collabora server in your browser if the browser requests accordingly. UCS creates his own certificate authority.

Integration with EGroupware

• Alternatively you can use EGroupware, which is also available in Univention App Center.
• Login in EGroupware with an Admin-Account of EGroupware
• Go to Admin -> Applications -> Collabora -> Site configuration
• Insert the URL for the Collabora server e.g. https://FQDN_OF_THIS_SERVER
• There are happening additional checks for the user "anonymous", which is required for Collabora and file sharing 
• Next step is to set permissions for groups, which should be able to use Collabora Online.  Either edit the User group or use context menu on the user group -> Access control and add checkmark for Collabora . So Admin can decide who is able to use Collabora in EGroupware.

FAQ

• How can I add the UCS root CA to the Nextcloud App?

• Run the following command as root user on your Nextcloud UCS server:

  cat /etc/univention/ssl/ucsCA/CAcert.pem | \
  docker exec -i "$(ucr get appcenter/apps/nextcloud/container)" \
  bash -c 'cat >> var/www/html/resources/config/ca-bundle.crt'						
  			
  			

• How can I add the UCS root CA to the ownCloud App?

• Run the following command as root user on your ownCloud UCS server:

  cat /etc/univention/ssl/ucsCA/CAcert.pem | \
  docker exec -i "$(ucr get appcenter/apps/owncloud/container)" \
  bash -c 'cat >> /var/www/owncloud/resources/config/ca-bundle.crt'
  			
  			

• How to install the Collabora Plugin in Nextcloud?
• Login to Nextcloud as user Administrator.
• Goto Apps → Office & Text → [Enable] Collabora Online
• Goto Admin → Collabora Online for Collabora specific settings
• How to install the Collabora Plugin in ownCloud?
• Login to ownCloud as admin user (username owncloud).
• Goto Market → Integration → Collabora Online → [Install]
• Goto Settings → Admin Apps → Show disabled Apps → [Enable] Collabora Online
• Settings → Admin → Additional for Collabora specific settings