Multiple RDS On Windows Server R2

[BigAllOverTech]

Hello, I am hoping this is the one place that can give me some clarity and help on a project. I am not a Server Admin, so my knowledge is limited when it comes to it, but I am great at following directions and that's what's gotten me this far. I appreciate the help given.

I run the Tech department for a a small Point of Sale re-seller company. We currently have a customer that has a Server running Windows Server r2.
We have a few Handheld devices, currently running Windows10, that are run somewhat slow when the POS software is loaded. Our solution to this was to RDP those
Handhelds into some of our other Terminals. It was working great until some updates from MS broke our setup. So we've decided to utilize the Server as our point for the RDS and I am having some trouble settings things up.
I have already enabled multiple connections. I set it to 99999 (unlimited).
I also purchased some CALs and had it activated. I currently have it by User.
Currently I have the Local account on the Server and I am able to run one Handheld into it
The moment I try to connect a second Handheld, I get the message asking which account do I want to disconnect in order for that connection to be valid.

What am I missing? Sorry if I sound like I am all over the place...I am. And I'm also under some pressure to get this figured out.

Again, thanks in advanced.

 

[Neemobeer]

Do you have all of the RDS roles installed? License server setup?

Roles You Need

If you're hosting the license server on the same server then you have the "Remote Desktop Licensing" role installed too

Then Create A Session Collection Resource Type: Remote Desktop

 

[BigAllOverTech]

I did add the role. Double checked to make sure I had the same options pictures above.
I am hosting the license server on the same server as the Remote Desktop Licensing.

I looked up how to create a Session Collection Resource, and it says to go to Remote Desktop Services, and then Collection.
Well, when I click Session Collection Resource, I get a message that says "You are currently logged on as local administrator on the computer. You must be logged on as a domain user to manage servers and collections."

So how do I go about that? Also, will this affect the day to day operations that this Server is currently used for.
Pardon my lack of knowledge here.

 

[Neemobeer]

So how do I go about that? Also, will this affect the day to day operations that this Server is currently used for.

That would be hard to say without knowing the server specs and what it's used for and how much resoures the POS application uses.

You are currently logged on as local administrator on the computer. You must be logged on as a domain user to manage servers and collections."

You need to logon with a domain account as in Active Directory that has administrative access on the server.