I believe that is the correct number to Courtyard by Marriott Jacksonville. Below is a link you can use to find other lodging options.
https://www.mayoclinic.org/patient-visitor-guide/florida/hotels-lodging

I just called the number. Use the prompt at the end to be transferred. When I had an individual on the line I asked if he was at that specific property and he said yes. I had asked the individual if it was possible to make a reservation with them directly and he said yes. Make sure you tell them you want an in house reservation as you have questions. Hope this helps.