Licence transfer from old accountant

Welcome to the Community, @karenkennedy.

Your client needs to reactivate their QuickBooks Online account so they can add you as their accountant. I'd be pleased to walk you through how to do this.

To invite an account in QBO, you need to have an active account. Know that in order to resubscribe your QuickBooks, you need to log in with your master admin access. If your client doesn't have this access, they may reach out to their previous accountant to transfer the role.  

Here's a link that you can refer for more insights about transferring user access in the system: Learn how to transfer or change who manages your books in QuickBooks Online.

Once done, you can now reactive the QBO account. To do that:

1. Log in to your QuickBooks Online company.
2. Select Settings ⚙ at the top.
3. Under Your Company, choose Account and Settings. 
4. Hit the Billing & Subscription, then Resubscribe, and enter the updated billing information.
5. Press on Subscribe.

To give you additional information about what will happen billing details and data if you've resubscribed to QBO, please read through this link: How to resubscribe or reactivate QuickBooks Online.

After that, your client can now invite you as an accountant.

Here's how to do that:

1. Sign in to QuickBooks Online as a master admin.
2. Go to Gear icon and select Manage users. 
3. Select the Accounting firms tab.
4. Select Invite. 
5. Enter your accountant's info and select Save. 

I'm just a few clicks away should you need anything else, @karenkennedy. Just leave a reply below to notify me. Keep safe!

Thanks @BettyJaneB  the previous accountant said they transferred master admin back to the client.  However, when the client logs in they just get an error message now.  They don’t really want to have to talk to the old accountant either. 
Is it possible from someone at QB to look on the account and see if my client does indeed have master admin and why an error message might be coming up?