I believe that it is the file “BeeRef-0.2.0-linux” you have downloaded, so you have to give this file executable permissions, similar to an AppImage. I believe this because its file-header is “ELF”, that is an abbreviation for “Executable and Linkable Format”, a very versatile file-format that can hold many different data-types.
Have you right-clicked the file, then chosen “Preferences” and then, in the next dialog, given it the permission to be executed?
If you want to call it directly out of Krita, you need to put the file “beeref.desktop” in Krita’s resource-folder into the subfolder “pykrita”, I suspect you’ll find it then in Krita’s toolbar-settings and can put it in one of Krita’s toolbars, if I understood the description correctly.
The file “beeref.desktop” has to be downloaded from the same page you got BeeRef from, if you downloaded it from Github, so:
Michelist