They have to use the password tied to their Intuit account to finish the invite process, @CherylR1. They can create one if they don't have one yet. I'm here to provide guidance to get this done.

To do so, they can select the Create an account link in the Accept Invite page. Once done, they can now proceed in completing the steps to finish the invite. 

For reference, check this article: Add and manage users in QuickBooks Online.

In case you want to add your accountant to help easily manage your books, just follow the steps in this resource to proceed: Add accountant users in QuickBooks Online.

I'm always willing to provide further assistance if you have other questions about managing user invites. The Community is open 24/7 so feel free to post again here. Keep safe.