The API was designed with the intention that each user would link their own Dropbox account, in order to interact with their own files. While it is technically possible to always connect to just one account for all users, we do not officially support this, for various technical and security reasons.
The Dropbox API does have a general rate limiting system that applies to all account types, but we don't have specific rate numbers documented for that, and we cannot increase the limits for any particular app, user, or team. Apps should be written to handle these rate limit responses automatically. Also note that not all responses with a 429 or 503 status code indicate explicit rate limiting, but in any case that you get a response with 429 or 503 status code the best practice is to retry the request, respecting the Retry-After header if given in the response, or using an exponential back-off, if not. I recommend referring to the error documentation and Error Handling Guide for more information.
