Nextcloud installation in keyhelp

I had a lot of difficulties with Nextcloud settings in conjunction with Keyhelp. I don't want to make a statement about the two software(s), it's just the reason why you have to read this crap. This tutorial describes individual paths and not an entire process. Depending on the system, a step may be missing or added. So if you have problems with your Nextcloud instance despite the instructions, feel free to open a relevant topic in the forum here ;)