The problem is now solved. I called Quickbooks to help with registration of the new computers. Even though they do not perform "technical support for QBDT 2016 ...

My QB DT 2016 for Mac is now up and running just fine. Thanks.

I purchased two used computers with Mojave OS.Today I called Intuit support and while they do not provide "Support for QB 2016", they did provide a verification...

We purchased used machines with Mojave OS so we can run QB 2016, but we cannot get them running yet.