Access denied or access not correctly managed

Hi,

Firstly, thanks a lot for your work on this plugin which seems very useful. But, I’ve a problem: I can’t make this plugin work. :s

Here is what I want:
Three groups and, for each group, 1 page (created by an Admin) which is available for everyone but only editable by the group.

Here is what I did:
Three groups with Editor access and with Read-access to everyone and Write-access to the group.

Three pages and for each page, I checked only 1 group.

Three test users:
The user A created as an Editor; (in the WordPress “New User” form)
The user B created as an Autor;
The user B with No Role (using the User Edit form), as said in this topic: https://www.ads-software.com/support/topic/plugin-user-access-manager-new-users-added-to-all-uam-groups

Here is the problem I have:
The user A is automatically checked to all groups (the same problem was raised in the previously mentionned topic)
The user B can’t see the pages (normal for an WordPress Author role)
The user C can’t even log in to the wp-admin ! An error message is showed: (approximatively translated from french) “You don’t have the sufficient permissions to access this page“

Am I doing something wrong ? How can I achieve what I want ?

https://www.ads-software.com/extend/plugins/user-access-manager/