I have a new build published now which should correct game save issues.
As far as the profile error for NW.js it looks like you may have installed NW.js and the game is seeing that install and giving a warning.
Here's some info I found on that:
https://forums.rpgmakerweb.com/index.php?threads/mv-profile-error-occurred-durin...
It looks like you can safely ignore that warning and/or delete that folder from your profile.