I have deinstalled newer versions of ubuntu, because they would not load different appimage versions of RT. Finally i found the solution. Newer ubuntus need a library called libfuse2 to start appimages. you will find a description of installation by a search in the internet (at your own risk). with ubuntu 24.04 it is a similiar but different libfuse, you will find out but i have not tried it. i write this to save your time as i wasted mine.