First once logged in to Ollie, visit the Settings page and click on Integrations.
Select the QuickBooks Integration image:
You will be prompted to complete a couple of preferences that are unique to your QuickBooks Online account.
Click on the Edit button - you will be required to fill out each of these sections before you can successfully connect.
Select the accounts that you have just set up, or had set up previously, and hit SAVE.
You're all set, and are now connected! You can confirm/test the integration using your next Ollie Order. If you have questions, please reach out to Support!