Works but shows incompatibility with default login

In general: The plug-in is a great add-on for using simple membership plug-in and it works.

After creating new editor accounts I saw that using these accounts in the wp-admin login the plug-in seems to cause an error after logging in. Nevertheless the user is still logged in.

When I disabled the plug-in the error was gone. After enabling againg the error occurred again.

I will uninstall the plug-in until this issue is solved. Until then only two stars.