For iOS 

At the home screen, tap on the sync button to sync your steps data with the server. Your Apple Health steps data should now be synced with Vantage Fit. To avoid any overlapping syncs, freshly open the Vantage Fit app once after synchronizing. 

For Android 

Navigate to the profile section of the app’s home screen and select the “settings” button. Within the settings menu, scroll down to locate the option labeled “Sync Activities” under general settings. Tap on it to synchronize your steps.