Activat Device CAD (Server 2019) - not RDS CAL

Hello,

I am new in this forum. I am dealing with Software Development for decades but administration of (Microsoft) Servers is quite new to me.

We have a single server running and 10 clients attached to it.
Now we need more clients to have access to this server and - as far as I was told - we need more CALs (device not user CALs).

If found hundreds of instructions on how to install "RDS CALs" and I was told that there is a difference between RDS CALs and normal device CALs for more users. (We do not need remote desktop).

So my question is:

How do I install the devices CALs in Windows Server 2019.
As I said we are not talking about RDS CALs.

Can anybody tell me how to do that?

Thank you in advance.