Documentation
The allowed roles section allows you to choose what roles will appear on the node grant tab. Just check each role you want to appear. Note that you can still set defaults for all roles as the admin user, these options just hide what is available on each node page.
For each node type on your site, you can set default role access permissions and choose if the grant tab should be available on that page. If the show grant tab option is not checked, the grant tab will not appear on the node page regardless of user permissions.
For each node type, you can also choose the default permissions for that type. To emulate standard Backdrop permissions, you would give anonymous user and authenticated user view permissions for each node type. Note that once this module is first enabled, no permissions are granted, so it is important to set defaults.
The default permissions for each node type will apply to any node which does not have permissions set, either at the time you submit the settings or when any new node is created. For already existing nodes, the defaults will apply only to those nodes which have not had custom permissions set on the node grants tab.