QB Issue Resolution:

You can instead use a trial version of QuickBooks Online to integrate to a third party app. To get one, please check this article: https://quickbooks.intuit.com/uk/

If you’re still unable to integrate it with the trial version, I’d recommend getting in touch with the Intuit Developers. You can reach them by visiting their Community forum: https://www.developer.intuit.com/app/developer/homepage

Resolution for Issue 'Can I use the QuickBooks sandbox account to test integration with a GoCardless sandbox account?' available: Yes (Solved).
Source: Intuit Community forum.

Can I use the QuickBooks sandbox account to test integration with a GoCardless sandbox account?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for GoCardless
Quickbooks Repair Pro will resolve it efficiently and affordably. Guaranteed resolution of your issue, or you pay nothing!

Error Recovery for GoCardless [Canada]
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