I reassigned the phone number from the company to me a few hours before I enabled SMS feature yesterday. It displays the error message (see original post's screenshot). Then, I enabled the SMS feature as we already reviewed, and I discovered that I could make outgoing and incoming calls to my zoom phone number, and I could send texts to this zoom number and read them on the zoom app, but I still cannot send texts from the zoom app. Then I realized that I wanted the number to be assigned to an individual, not the company, so I unset the phone number from the company, and set it on me as an individual. Yesterday when I first started, I had the number assigned to the company. More about how I may have gotten into this situation: An hour or so before I made my original post, I enabled the SMS feature. The number has been assigned to me personally (and has not changed assignment) since a several hours before I made my original post.

Attached a screenshot showing that the number is assigned to the correct user.

Zoom phone number customer service