Thanks for posting back on Community!
Can I please confirm that you are trying to submit your final VAT quarter for HMRC? If you already have a HMRC account set up you can link this to QuickBooks for your submissions. QuickBooks Online is MTD ready for the next tax year please see this post here with regards to Making Tax Digital with QuickBooks Online.
Please also see this article for linking to HMRC.
Please let us know if there is anything further which we can help with.
