Failed to load collabora online

I work with Nextcoud Version 16.0.4 on my own account, hosted by .
I have installed Collabora Online as an app.
I have installed an empty folder with this url: .
In the configuration I added the following number to the url above:
Which program do I have to install into this folder, so that Collabora Online can work together with my account?
If that is not possible, which other url can or should I use?
Thank you for your cooperation,

URL (and Port) of Collabora Online-server

You need an installation of collabora online as well. The installation for home use is a docker image that you need to run. The app you install in nextcloud is just an app to communicate with the collabora service.