Fitbit Inspire 2 won’t sync with iMessage

I’ve already gone 4 rounds with tech support thru Fitbit and while I’ve done everything they’ve asked 4-5 times, nothing is working. I decided to ask here because suddenly FB messages are showing up on the Inspire but iMessages still won’t. Can someone please tell me why my iPhone (XR, up to date iOS 14.6) iMessages will not sync to my Fitbit and how to fix this??