Not sure if this has been addressed before. Is there a yum install or repository available for MC21 or upcoming MC22 (which I just pre-purchased.)
Did the steps in the sticky at the top of the forum not work? They are for Fedora 22, so there may have been a change, but if they're not working, asking in that thread is a good way to get the attention of Fedora users (I don't run Fedora so can't offer advice).
https://yabb.jriver.com/interact/index.php?topic=99329.0Does it work like a gui app under gnome?
I'm not sure I fully understand the question, but JRiver MC runs under Gnome just fine (I use it with Gnome on Arch every day), and it is a GUI program (it requires an xserver to run). It's not likely to show up in Gnome Software if that's what you're asking, you'll need to install from the command line, but after install your interaction with the program will be in the GUI, and JRiver MC should show up as an application in the icon list in the overview.