Windows Server 2019 for development IIS question

Built a new stand alone server for use in web development. Got IIS running. Migrated all our sites from our live server on the internet to this one.  At this point I am lost.  We can create a test site with a default web page and reach it on the LAN using the IP address of the server. However, if we shut that site down and start one of the ones from the migration we cannot get to that site.  Our expectation was that we would get the same page as we see on the live site.  But nothing.  It seems pretty obvious that what we did is not the correct way to go about it but we really don't know where to go from here. 

How does one copy a live web site to a standalone  server on the LAN and get it to work?

I realize I am demonstrating just how out of my wheelhouse I am here, but be gentle.  I do have a LOT of server/network experience, but really none around IIS other then getting it to run.

Thanks