Hmmm! I googled the error message and it's telling me that it may have something to do with incompatible save data between devices? I'm really not sure why this would be affecting you though since an itchio version of the game wouldn't use cloud saving like steam might.
I'm very sorry I can't be more helpful, I've never seen this particular error before ^^;
If you'd like to look into it more yourself, a good search term would be "Renpy ImportError No module named Revertable" <- that's the name of the program the game was made in and then the name of the error message