[RMMV] HELP WITH VICTOR ENGINE"S FOG PLUGIN

I downloaded the plugin from Victor engine's blog and it won't let me add the plugin to the project folder because of a script error, it's in line 17 character 5 "data manager" is undefined. code 800A1391.
I didn't touch anything so idk what the issue is since no one else seems to have had the issue. Any tips on how to fix it are greatly appreciated.