If you don't want to share your activity to the 'Community' feed, simply just press 'Skip' after logging your activity. Your step count will update without posting to feed.
Note: Information collected from the Steptember app, including location data, is stored in the country in which the Steptember licensee operates (Australia or US), and is used to provide an engaging and rewarding Steptember participant experience offered by the Steptember app.
For more information please see:
Please also check out more information on the Steptember app here!