Many people complain, and it is logical, of the low maintenance of the Community Document Server application; see among others this github ticket.
I therefore launch an appeal on this forum in order to be able to relaunch this application with maintainers of goodwill and available.
Thank you all for your help,
Sorry i do not use OnlyOffice.
But maybe someone can confirm that the app ONLYOFFICE is the correct Connetor app. Also i found this integration guide (not tested).
And perhaps someone can also post actual information for Nextcloud Office (Collabora Online).
If up-to-date information is posted more often, perhaps outdated information will be found less often. 