Happy to provide some insight on the user invite process in QuickBooks Online, @klwendell.
The user that you've added needs to accept the invite that was sent to the email address provided in their profile. Accepting the invite on their end is super simple and only takes a moment. Have your new user select the “Let’s go!” link in the email, which takes them to a sign in or account creation page. They need to sign in or enter info to create a new account.
Note: If your user sees a sign-in page and isn't sure why, it’s because their email address is already used with an Intuit account. This could be for a different product, like TurboTax. It’s fine for them to sign in with that email address if it’s theirs. If they’re not sure how, they can select I forgot my user ID or password at the bottom of the screen.