Base station hook-up.
How do I set-up my base station if I already have an Airport Express (for iTunes)?
iMac 21.5″, macOS 10.15
Question marked as
Your Airport Express could be setup in a number of different way.. all of which will work for iTunes.. so we have no way of telling you how you can setup the base station.. which I assume means an Extreme.
In most cases the method is simple. Plug it by ethernet to the main router if Non-Apple.. there is no choice in this.. even if the Express is set to join by wireless the Extreme cannot. If your main router is already Airport of some sort.. then you can use either ethernet or wifi for operation of the Extreme.
Assuming also you factory reset the Extreme just run through the setup wizard in Airport Utility in your Mac and it will set up the Extreme for you with minimal interaction.
My only comment against the above is if the Express is your main router.. I would suggest a swap. Put the Extreme as main and the Express as extender. Express is a toy router.. and is really limiting internet speeds for anything above about 90Mbps.
If you have issues post screenshots of the setup with express from airport utility.. so we can figure out how it is currently setup.