RGT does not support automatic uploading to Garmin Connect. Only SYSTM does. To get it into Garmin Connect you’ll need to manually upload the FIT file. There is a recent thread about this too: Garmin needs to be added as a Linked Account
As mentioned on 🚀 New feature: Outside rides (and other Wahoo cloud activities) now appear on the SYSTM calendar further down the road they’ll open it up for non-Wahoo but that is not yet present.