I've acquired FPS assets in a online course and I got the skeletal mesh down and followed along to the Details panel, down to Animations - Anim to Play to select animation file "Arms_idle". In the browsing option, I typed "idle". As you may know, typing this in will pop up "Arms_idle". However, it did not. It was empty. So, I went to the Content Drawer and browsed there. It showed up. I dragged the file to Anim to Play but it didn't allow me to do that. For your information, the instructor is using an older version of Unreal. I am using the latest version. Hope that's okay.

If you know how to fix this problem, please leave a comment below! Thanks