Pushing data to my app

DylanC As Здравко said, take note of what root you're using and make sure you're working in the same location for each user.

Also, note that apps with the "app folder" access type get an app folder in each user's connected account, and these app folders do not sync with each other. If you have multiple connected users and need their content to sync to each other, you'd need to use "full Dropbox" access instead, to access a shared folder or team folder.

And in addition to the Team Files Guide that Здравко linked to, the File Access Guide and Detecting Changes Guide may be helpful.