Unlike Ren'Py or other games where the saves are (also) located in one of the
AppData folders, RPGM games have their saves in the directory where the game is stored in--namely, the "save" folder. *Of course, some people have played these games from a compressed file (i.e., downloading a game and running the game without unpacking) in which case save points cannot be created.
Example of where a save might be:
Say, I have a game called "Game One". I've downloaded it and unpacked it into a folder called "RPGM" located in drive, say, G. Thus, the pathway should be something like:
"G:\RPGM\Game One", for this instance. In there, you'll see a folder called "save". That's where your saves are.
"G:\RPGM\Game One\save", and the files will have rpgsave or rvdata2 (or something) as their extensions if you have the options of viewing extensions turned on. Sometimes the "save" folder is not present until a save point is created. In fact, this folder can safely be deleted if you want a reset the game from scratch.
I hope that helps. Just one disclaimer, as I currently have no RPGM games installed at the moment, all of the above is from memory. It should be accurate nonetheless.
Edit: Mind you, that's where the default location of saves go--right in the game's directory. However, if the developer changed the default save location from within the game's script using its data manager, then it could be anywhere. I hope you're not dealing with a weird case like that. Fortunately, RPGM developers messing around with save locations is quite uncommon. (I apologize if you received a few duplicate alerts from within F95 as I was having a little bit of an issue getting the answer posted--weird forum issues at the time of this post.)