[hlloyge]

You can give up hope. Fritsch wasn't active since months and he already said, that he's not going to support this thread any further. So there's nothing to complain if anything from the how to doesn't work if you don't use the OS versions mentioned at the how-to. Btw..this thread wasn't updated since over a year ago. So...what do you expect

I'm sorry, first thing I've read is the first page, and never did I saw that information there. When I posted, there was 5 months old post there. Do you really want to know what do I expect? 

This thread is for 18.04 and 20.04 only. If you choose to install 21.04, you are on your own. But I see, that you mentioned to install 20.04 but obviously you are now running LibreELEC. So this is the complete wrong thread to discuss LibreELEC related questions. Please open a new thread (probably at the LibreELEC forums) and mention your problem over there. 
If you want to get your install-problem solved, then install Ubuntu 20.04 again and get us the following ouputs:
apt-cache policy kodi

I solved the problems I had, which were based purely on my lack of knowledge about LE inner working. But that is not the thread's theme. I did try 20.04, yes, but it didn't work. Doesn't matter now. I am sorry Fritsch quit supporting linux installation, and I am more than sorry for you dropping KodiBuntu. Oh well, times change. But please, the info that Frisch doesn't support this thread anymore should be at the top of first post.