Once their enrollment is complete, your family members will be able to download ActiveFit from the App Store or Google Play store and log in with the user name and password that was set up in Step 3 of their enrollment.
Open the GoogleFit app.
Go to the Profile section and tap on the Settings icon.
Under Settings, go to "Tracking Preferences" and make sure that "Track your activities" is enabled.
Usually Google Fit will try to synchronize with their servers when the phone is above 50% of battery life and is connected to WiFi.