Please be aware that when people talk about RAWS they often get confused between the license and the program you install onto a remote system
With regards to the RAWS license you need one for every remote Windows System or device backed up via shares and theses license get installed on the media server. If teh remoet server iin question contains a database technology (Exchange, SQL, Sharepoint, Domino, Active Directory etc) then the agent for databases does include the allowance to backup data on the same server that would be protected by RAWS as such you do not need a RAWS license and a Database license for this scenario.
As pkh has indicated when you backup over shares because no agent sofwtare can be installed then the message you quoted will always be seen.
Active Directory is an odd one as you can back it up without needing the Active Directory Remote Agent (ADRA) so can just use a RAWS backup - however this only gives you the ability to do a DR restore of the domain controller. If you want granular restore you will need to invest in ADRA. As such for a remote DC you can choose whether to buy a RAWS license or an ADRA one depending on what restore capability you want..
With regards Active Directory