Manuskript is unfortunately a very buggy piece of software, with regular freezes and crashes. And the UI is, in my opinion, extremely clunky and unintuitive. I love open source software, but I can’t in good conscience recommend anyone use it.
Scrivener did have a linux version that they stopped developing, and they ended up giving away the last version. Someone packed it in an appimage for easy use, should be able to find it if you search appimage scrivener. It’s a pretty feature complete release, and still works well to this day.