Out of curiosity and to take as many possibilities into account, do you by any chance have OneDrive (or whatever that MS cloud is called) installed / enabled? The folders / files that should have gone to the local Documents might have been redirected to the OneDrive location. I didn't experience it myself, but there were some posts about that in the past on the forum (too lazy to use the Search button to find them at the moment).I have been having the very same issue also for some time now also, Rainmeter just will not create a folder in Documents, I have done the clean uninstall and install and reinstall as admin, none of the help in this thread has corrected the issue.
Also after installation there is no desktop icon and no file association for .RM files
EDIT: Alright, brushed off the laziness and here is the result (I only included SilverAzide as Author cause I distinctly remember him mentioning this as well):
https://forum.rainmeter.net/search.php?keywords=onedrive&terms=all&author=SilverAzide&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
Or, even more specific:
https://forum.rainmeter.net/viewtopic.php?t=41900
Not sure if it helps, but hey, it's the first among the few potential culprits for this I could think of.
Statistics: Posted by Yincognito — Yesterday, 10:20 pm