OmniFocus for the Web is designed to connect directly to Omni Sync Server, and associates your subscription to a specific sync server account. If you try to subscribe to OmniFocus using an Omni Account other than the one you use to sync your data, you’ll receive a warning that you won’t be able to access your sync data using OmniFocus for the Web.
To subscribe and sync using the same Omni Account, sign into the Omni Account you use for sync in OmniFocus Settings > Omni Account. If you’re already signed in to a different account, use the Sign Out button at bottom of the screen.
Once you’re signed in to the same Omni Account in both spots, start the subscription process again from Settings > In-App Purchases.
