So, I failed setting up MariaDB on my server. There was an element missing after installing it and as I'm just a curious archivist, I will stop it right here. I already put too much effort into setting up my personal server where I just could have used unRAID.
Also the CollectiveAccess website is down for at least the last two days. At least for me.
I wanted to look into CollectiveAccess again to see if it's something I can recommend to my bosses. But for that I would have loved to test it on my machine, because I would be the one setting up the archive database. Unfortunatelly we do not have IT staff I can ask for help.
Anyways: I wish you all a great expereience with it!