I believe the i pad app https://wiki.roll20.net/Roll20_for_iPad_and_Androi
... (if this is the app, and not roll20 within a browser) is only a playing aid. Meaning, you can edit your sheet, make rolls, use chat, compnedium access, etc. but not actually manipulate tokens, see the map, edit the vtt, etc. Be advised that currently the application must be used in conjunction with a campaign started via the free-to-use Roll20 Virtual Tabletop. Apologizes if you are trying to use roll20 within a browser.