Hi Micky594,
There may be a few reasons why we're unable to connect your QuickBooks to HMRC for MTD filing.
First, please check that you have entered your VAT registration number correctly within the settings by going to Taxes > Edit VAT > Edit settings. The number should appear here in number format only without spaces.
If this doesn't fix the issue, please get back to us below to confirm if you've received th email from HMRC confirming you've successfully registered for MTD.
Thanks