I had the same issues that many other linux users have.
Basically, launching a freshly downloaded Manager AppImage will not work getting the dreaded:
execv error: No such file or directory
Trying to inspect the AppImage to learn what went wrong, I would get
Squashfs image uses (null) compression, this version supports only xz, zlib.
Diving into the rabbit hole I came across some github issues that mentioned completely removing AppImageLauncher would resolve these problems, so I tried it, and it did.
So if you have problems launching Manager using an AppImage on Linux with one of the errors mentioned above, try uninstalling AppImageLauncher and see if that works for you:
sudo apt remove appimagelauncher
Download latest Manager AppImage and check.