I can see the urgency for adding your accountant to your QuickBooks Online (QBO) account, @Feasta. That's why I'm here to ensure you can complete the process and get the help you need.

Giving your accountant access to your QBO company file and accounting info makes it easier for them to review your books, make corrections, and fix any tricky transactions, especially during tax season.

Since the system is asking for verification, I'd recommend logging in first to the One Intuit Account (OIA) Manager page. This will help verify your account and manage your data easily. You can either access it here or from within your QuickBooks offerings and services. To do this within your QBO account, here's how:

1. Go to the Profile icon (beside the Gear icon).
2. Select the Manage your Intuit Account link. 
3. On the Intuit Account Manager page, choose the Sign-in & security menu.
4. Go to the Phone section to check your contact info, then select Verify.
5. Choose how should we contact you and select Continue. 
6. Follow the on-screen instructions to complete the process.

Once done, log back into your QBO account. Then, add your accountant again through the Manage users window from the Gear icon or visit this article for the step-by-step guide: Invite an accountant to review your accounting in QuickBooks Online.

Also, when you add a user in QBO, you can manage their roles and limit their access to specific tasks. To know more about managing user permissions, I'd recommend checking out this article: Add and manage users in QuickBooks Online.

Please keep me posted on how it goes in the comments below. Should you need further assistance or you have other concerns in managing user roles or permissions in QBO, I'll gladly help. Take care and stay safe.