Within Link, you can enable an account selection pane, which allows an end-user to select one or more of the account(s) at their institution. When enabled, this pane will display once the end-user has successfully authenticated and is the final step of the Link flow:
Although an end-user may only select some of the accounts associated with their institution, our API will still provide access to account data for all of their available accounts at the institution. Note: there's an exception for Items created via Auth's Automated Micro-deposits and Same Day Micro-deposits flows: the API will only provide account data for the selected account.
If account selection is enabled, the Connected pane will be skipped and the onSuccess callback will fire after the end-user selects their account(s). The account(s) selected by the end-user during this pane will be listed in the accounts object of the onSuccess callback.
You can configure the account selection behavior through the "Select Account" pane within the Customize menu of your Dashboard.