No the mods don't have to be updated. This has to do with the Madden update. Basically what you have to do to fix this is the following:
1. Go to the location where your Madden 19 is downloaded for me this is D:\Games\Madden NFL 19
2. Delete the file bcrypt.dll and the folder "ModData"
3. Go to the folder where your Frosty Mod Manager is installed for me this is D:\Madden 19 Mod Manager
4. Click on the folder ThirdParty and delete bcrypt.dll
5. Go to the original .rar download of Frosty Mod Manager you have not sure if it matters the version. I'm using FrostyModManager_v1.0.4.3.rar go into the folder ThirdParty within that rar and drag and drop the brcypt.dll to both locations you deleted it from. Then launch Frosty Mod Manager and it will take you through the original process ( all your mods will still be there don't worry)
There is no bcrypt.dll in either of those folders. Also there isn't one of those files in mod manager rar either. I even downloaded a new mod manager.rar. Weird