WIndows 2016 Remote desktop licensing

Hi,

 

I want to setup Terminal services (RDS) on windows 2016 server. I am estimating 50 concurrent RDP connection to this server but i was told by Vendor that RDS is inbuilt in 2016 and i do not need to buy separate licenses. 

 

But i believe, i need to buy 50 CAL for RDS...is that correct ?