CacheDrives do not store login information when using Active Directory mode. All authentication information is passed to the domain controller, which verifies access, group membership information, etc.
The CacheDrive will gather group membership information every time the user logs in to a share. If the user's group membership is changed in the DC, however, this will not be updated on the CacheDrive side until the user logs in again. Therefore, these changes will not take effect immediately.
If the administrator applies a group membership change that affects many users and must be put into effect immediately, one option is to restart the SMB server, which will force all users to login again. This can be done in MCM from the Devices ->Maintenance dropdown.