I've got a few troubleshooting steps that we can try, bevsigma.
If you signed up for the QuickBooks Online for Accountants version, you'd have to let your client add you to their company file first. You can give them this article for the steps: How to manage an accountant user in QuickBooks Online.
On the other hand, you can try some browser-related solutions if nothing happens when clicking the black toolbar.
Here's how:
- Open your QBO account in a private window and see if you can get the black toolbar to open.
- If it works there, clear the cache of your browser.
- Try a different browser if you get the same result.
Please keep me posted on this. I'll get back to you if you need more help.