The current version of the Mod Loader is only compatible with version 1.03.0919 of Sonic Mania. It is not compatible with the cracked version currently available. If you want to use mods with an older version of the game, you will have to find an older version of the Mod Loader. This tool allows you to use mods and cheat codes in Sonic Mania.
Just a heads up that your mod loader has the default Visual Studio executable icon. Maybe you should consider changing it to something that's not the default so that GameBanana can represent the mod loader properly?