I am hoping for someone to provide a better answer but since I had to get these computers set up and deployed here is what I did in the interim.
I created an email account on my email server for each machine, so 20 accounts.
The accounts were named after the unique machine name @mydomain
Then when I entered the office 2019 product key into each computer I entered the new email account when prompted.
This of course was quite cumbersome because I had to verify the new account which meant I needed to retrieve the code that microsoft emailed to each account.
I had to temporarily forward the email from those new accounts to my account which was not good since I am just setting these up, not maintaining them.
After that I had to solve a puzzle on each computer to prove I was a human. (The puzzle was not a simple "type the letters" question. It had between 15 to 20 question screens per computer asking me to select the graphics so that was about 350 screens total that I had to click through. I am not kidding!
Finally after that I was forced to provide a phone number to allow the account to be created.
When I didn't provide the phone number it sent me back to the beginning and I had to start from scratch again and reenter the product key and answer the questions again.
Also Microsoft then complained that the same phone number was already in use so I had to come up with 10 unique phone numbers as it only allows the same phone number to be used twice. (It would not accept burner numbers... I tried that)
So I had to contact 10 of my colleagues and tell that what I was doing and ask them to send me the code they received from a microsoft text message.
Of course it is a weird thing to ask someone else to send me the code they received on their phone. very sus'...and what happens if any of them try to register with microsoft in the future and it complains that their number is already in use?
Finally I had the 20 accounts created and I was able to get office 2019 running.
This was unnecessary busy work and added an extra 30 minutes per machines multiplied by 20 machines.
I did set up the machines concurrently so there was overlap but I still wasted at least three hours on this.
Are there any other alternative?
Is there a phone number I could have called that would have allowed me to key in the product key and provide me an activation code.
I looked but I couldn't find that option for this version of office.
I remember not very long ago when I just had to enter a retail product key to activate office.
I am going to have to do this again in another month so I would like a better answer.