You need (HMM) – the official mod launcher.
Additionally, ensure xinput1_3.dll is not missing. If it is, your DirectX is outdated. Run the . sonic generations mods not working link
If you're still experiencing issues, providing more details about your problem (such as error messages, the mod you're trying to install, and your platform) could help in getting more specific advice. You need (HMM) – the official mod launcher