What is the fastest way to allow users to RDP into computers?

I have a network with about 20-30 computers which are all on the same network/domain. I just created a non-admin user and tried to RDP to the machines but keep getting the error “The connection was denied because the user account is not authorized for remote login”. I added the user to the Remote Desktop Users group which didn’t work. I also tried to install Windows Server Essentials Experience and to do it through there, but you have to join each computer to it anyways, so it wouldn’t be different from going to each computer and manually adding the user to Remote Desktop Users local group. RDPing for administrators works fine.

Is there a way I can enable RDP to all computers from just the domain controller so there’s minimal work involed?