Problems with r2modman

I am trying to mod various games on my steam deck with r2modman - however, in ever single tutorial I've looked at and followed I end up with the same problem. The app image isn't opening! Every time I try to open it it says the file type cannot be opened and shows a bunch of text if I push further. There is a setup/installer folder that comes with the download from thunderstore, but after I go through the initial menu and launch it through a game, it says the app is installed but nothing happened (I've looked all over my files - there's nothing). What am I doing wrong?