Ensure the mod is built for Repentance or Repentance+ . Older mods for Afterbirth+ (AB+) may still work, but those specifically for the Repentance era are more stable.
If you aren't using Steam or prefer to manage files yourself, you can install mods manually by following these steps: the binding of isaac repentance mods no steam updated
Since you aren't using the Workshop directly, you will need to find the mod files elsewhere. Community members often use third-party downloaders or find projects on GitHub or Nexus Mods. Ensure the mod is built for Repentance or Repentance+
To get the most out of your run without the Steam Workshop, look for these highly-rated, frequently updated mods: look for these highly-rated
Significantly speeds up animations for slot machines, blood banks, and beggars, reducing the "min-maxing" downtime during runs.