Totally understood, seems like there must have been a lot of backend / technical work to get this far - did it come from a personal need/itch?
As you are asking for permission to access to people's personal / private files I think it's really important that the site comes across as very professional so that potential users feel they can trust the site with connecting the different services. Not sure if you are explicitely asking for feedback and ideas but this definitely the area I would work on - creating a polished feel, particularly on the landing page.
