Later today we came back to sleuth the problem and decided to check the Bandlab Assistant web link that goes to https://www.bandlab.com/feed and found a notification that informed us that we had to confirm our email address. We are a new account to Bandlab! After we had verified our email address, Cakewalk was able to activate (we did launch Bandlab Assistant as the Administrator user, so not sure if that's also part of the puzzle). After activation, we just launch Bandlab Assistant, then launch Cakewalk - as a normal user - and all is OK now, Cakewalk can save stuff! If this email confirmation was indeed the final puzzle piece, then I think this important bit of information should be an emboldened part of the FAQ.
Bandlab/Cakewalk install activation is still broken as of 2020, so you will only be able to install Cakewalk in Demo mode. That is to say, the "free" version is just a ruse. Using the recommendation to uninstall and reinstall as Administrator also does not work. Staff does not actually attempt to perform this task as part of quality assurance. Also, the following URL references a non-existent internet site: https://bnd.la/cakewalk-activation. This post was written by my Dad. We're both frustrated with what Bandlab has done to Cakewalk. EDIT: I think we found the missing puzzle piece: if you have a brand new Bandlab account as part of the requirement for installing Bandlab Assistant and Cakewalk, be sure to check the Bandlab feed for a notification that says something like, "Check your email inbox for the email verification link". Once we did this step, Cakewalk was activated and was able to save files!