How to Setup 2 Servers, 2 computers on one account

Doing some research but can’t seem to find the method to do this.
I have a mac mini running server 1. port 32400 working for 2 years
I now have a sinology NAS and installed PLex Media server as well and on port 32401

the Synology PMS asks me to log in with my account (which I do) then the server 1 shows up.
What are the steps to log-into 1 account, then choose which server I wish to use (top=left) menu

Thank-you
BV