I guarantee that not one single person who is having this issue is closing the authorization window prematurely. I'd upload you a video of what is going on, but I can't attach a file bigger than 9mb, so the best I can do is another screenshot. I have all pop-up blockers, Content Blockers, and anything else that could possibly keep Quickbooks from establishing a connection to Shopify disabled, but as you can see in this screenshot, it is failing before the authentication even attempts to happen. Your API is broken. Finaloop connects to Shopify Balance just fine, but they authenticate with Plaid.