Make sure you have the most up-to-date version of Frosty Mod Manager (1.0.6.1) – you can download official Frosty Mod Manager site.
Next, get the DatapathFix Plugin by Dyvinia for Frosty – you can download this HERE. (Click on the DatapathFixPlugin.zip under Assets of the latest release.)
Extract the contents of the ZIP into the FrostyModManager Plugins folder.
Run Frosty and under Tools > Options > Launch Options, disable Platform Launching.
Check your Installed Plugins to see that the DatapathFix is installed correctly.
Exit Frosty.
Run the EA App as Administrator. Then run Frosty Mod Manager as Administrator, and launch the game.
That’s it! I got all my mods to work this way.