From a Filr perspective, users can get the required permissions to access files and folders in one of three ways:
Directly: Users are assigned permissions to the files and folders.
Group Membership: Users inherit permissions to the files and folders through membership in a group that has been assigned the permissions.
Net Folder Proxy User: Users receive and accept Filr share invitations. They can then access the shared files and folders through the assigned Net Folder proxy users that have the required file system rights.
User roles relative to Net Folders are not assigned. They are automatically derived from users’ permissions on NSS and NTFS file systems.
As explained in How Users Get the Required Access Permissions, file system permissions can be directly assigned or inherited through group membership.
User roles relative to Shares are assigned by the user sending the invitation.
Users sending invitations can only assign roles up to the level that they have.
Users receiving and accepting share invitations might or might not have direct rights on the file system, but that is irrelevant. Individual user rights do not affect Shared with Me functionality. Instead, Net Folder proxy users interface with the file system for everyone who is functioning in a sharing role.
If users access a folder through Shared with Me to which they also have file system rights, their functionality within Shared with Me is defined by the sharing role they were granted with the share invitation, even though that role might provide more or fewer access privileges than they would have through their Net Folder connection to the same folder.