I create a user and add it to group
Remote Desktop Users but I cannot still remote using
mstsc. The error message said the user/group doesn't have the right to remote.
My question is how can I grant this right to the group?
Check in the group policy editor (gpedit.msc) under Computer Config > Windows Settings > Security Settings > Local Policies > User Rights Assignment. Find the entry for "Allow log on through remote desktop services" and "deny log on through remote desktop services", and see if the groups in question are in either of those categories. Deny permissions will usually override allow permissions.