You can usually resolve this issue by reauthenticating to the mod menus;
1. Select "Mod Browser" from the main menu
2. Press the Triangle button (PS4) or Y button (Xbox) to open up the "more" menu (bottom right)
3. Scroll down to the "Log Out" option at the bottom of the list
4. Confirm you wish to log out of mod.io
5. Go back to the mod browser, and follow the instructions to authenticate
Please note: If you are on PC, simply use your mouse to choose the corresponding options.