If you purchased your Dropbox subscription through the Apple app store, you'll have to request your refund from Apple directly.
To request a refund, follow these instructions from the Apple support page:
- Sign in to your App Store account here and report a problem with a purchase.
- Click Report a Problem next to the Dropbox app.
- Choose a problem, write a description, and click Submit.
- Apple will contact you with a decision on your refund request.
Note: Apple only accepts refund requests for purchases made within the last 90 days.