Please find information from our Help center on connecting to Fitbit - https://support.grokker.com/hc/en-us/articles/360000423472-How-do-I-connect-my-Fitbit-or-Garmin-account-with-Grokker-

How FitBit works with Grokker:
From the time you connect FitBit to Grokker, FitBit will only sync back up to 48 hours, but will then sync your workouts going forward.
We record activities tracked by devices only. Manually entered activities are not used.
We only record the following FitBit Activities: walk, run, bike, swim, sport, hike, elliptical, aerobic, training, exercise, and fitness.
We do not sync any steps.