Newbie Guide to Unattended Remote Access
On the very first screenshot (host computer) you can see an option for "Encryption reguired" is switched On and you can see a part of encryption key actually. The second screenshot (in the middle) is from a computer trying to access the first one. It has also encryption reguired option and the key is the same. And as you can see on the third screenshot, the host computer is still requesting PIN.