That is very strange since the only way to invite users is from within an open, registered, fully functioning company file.
The link in the email should take them to a page to open their new intuit account if they dont have one yet.
Thanks for chiming in this thread. Happy to lend a hand for you and your client, so they can access the QuickBooks Online company. I have a bunch of solutions to resolve this.
You might want to ask your client to see if they have an existing account or not. If they don't have it yet, you'll want to let them create one. Just like what john-pero said, they will be redirected to the account creation screen if they don't have one yet (after opening the invitation email).
Also, this might be an issue with the link itself. Try deleting and recreating the invitation email again to fix this. Here's how:
Resend the invitation with the correct email address by clicking the Add user button.
If they've forgotten their password, let them click on the I forgot my user ID or Password link (in the login page after accepting the invitation).
Another solution we can try is to clear their browser's cache. If it's full, it can cause QuickBooks Online's webpages (including the invitation link) to act a bit strange. To confirm this, let them use an incognito window or browser:
Inform them to click on the invitation link, then copy and paste it to the incognito window. Let them log in using their account from there. Once done, have them clear their browser's cache for good measure. It'll help fix webpage issues in the long run. Alternatively, they can use a supported browser.
After accessing the company file, I'm sure you or your client has tasks to do in QuickBooks Online. Check out our articles if both of you need help.
I'm always here to offer assistance in the future regarding QuickBooks Online. Just name your issue and add your details in this thread. I'll get back to you as soon as possible. I hope you had a wonderful weekend!
Thanks for joining this conversation, @ResourcefulRemnant.
We received reports regarding other users having the same issue in QuickBooks Online (QBO). A ticket was already created and forwarded to our Product Engineers. They're now working to fix this as soon as possible.
In the meantime, I highly suggest contacting our Support team so they can add your details to our notification list. This will also help our Engineers determine the number of affected users. An email notification will be sent to you once this has been resolved. I'll also inform you here when we get the update as well.
Here's how to reach them:
For more information about what to do if invited users didn't get, or can't find, your email invitation to use QBO, consider checking out this article for future reference: What to do if invited users did not receive your email invitation.
Please know that I'm only a few clicks away if you have any other concerns. I'll be more than willing to assist. Have a great day!