One of QuickBooks' requirement for the integration to work is tax codes. There's a way to activate tax codes in your QuickBooks account even if your not yet registered.
Please set the appropriate tax code for your account and follow these steps:
*The steps show GST as an example. (AU version)
Step 1: Setup/Activate GST (Tax code) in my account settings
Step 2: Create one invoice or expense (Set it to $1 for example)
Step 3: Select 'Out of scope GST'
Step 4: Go to my Advanced Account Settings
Step 5: Set my Default Tax Rate Selection to 'Out of scope GST', and you're done!
For the UK version, simply set the tax code/VAT to 0%. Then, set the VAT registration number to 00000000 for it to work.
If you need help with anything, we are here for you :-) Just message us in-app by clicking on the green chat icon on the bottom right-hand side, and one of our friendly staff will give you a hand.
Please note that different versions of QuickBooks have different options, so it's better to seek support from QuickBooks customer service.