quickstart: HTTP 403 when searching for institutions

When I try to search for my bank (Capital One 360) using the institution selector, a spinner briefly appears after I type a few letters, and then I get the following message: Your search request timed-out, please try again with a better connection

Looking in the inspector, I see that a GET request to https://cdn.plaid.com/institutions/all/search?q=cap returns an HTTP 403 status. Opening that URL in a new tab gives the familiar AWS access denied error page.

The steps to getting this running seem pretty straightforward, so I don’t see much room for user error here.