I had to replace my phone and when I try to use the app. It is making me reset my device saying it is requested to a account already. I signed into my account but it will not connect
The prompts in Connect are often confusing. Instead of connecting to your existing account, you ended up setting up a new account. Just log into your old account and you should be fine.
Does syncing over the USB cable to Garmin Express work, and making the data visible in your Garmin Connect account? What is the version number of the the GC Mobile app? (see it in GC Menu » Settings » Version)