For the first thing, I want to underline that installing a terminal server on a domain controller is not a best practice and is not a very good idea. But in some cases, in small environments, where you have maybe only one or two servers, you have no choice and you must to do that.
It’s not a problem to install a rule, but you will have a problem when you will try to logon through terminal services with a user who is not an administrator. There you will receive the error that this user is not the administrator and it has no logon true terminal services rights. On a non-DC server, this is simple to solve in local users and groups console, but this users and also the console is disabled on a DC.
You must do that in gpedit.msc. There you have to enable Allow Logon through Terminal services right to the desired group of users (look at the picture).
You must think also about the printing issue. There is a security issue on Spool folder, because the user does not have sufficient rights on it. To solve this problem, you must open a Command prompt as Administrator and go to the folder C:WindowsSystem32spool. Here you have to run the command Cacls.exe PRINTERS /e /g users:C and restart the computer. Now you are able to print.