Hello,
I am new to NextCloud so I decided to activate a free account on opsone-cloud.ch .
All is good in there, but Collabora is not present as it was in the online demo account. I checked the settings and I don’t see an app section where maybe add Collabora.
At first I would recommend to contact the support of your opsone-cloud-Hoster and ask them what need to be done to get access to the Collabora app. Very often providers are reducing the functions of a free account to a minimum to get a stable and sharable setup. Apps like Collabora, which require more resources are very often only available if you pay for a service.