I am doing Pro Advisor training. Why is there no create button at the top of my client screen?

The create icon was moved to a different position, celia52-cm.

A new QuickBooks interface was released last November. As part of the update, the Create icon was moved to a better position and renamed as +New.

On the left panel, you can create transactions such as invoices, sales receipts, and check and other transaction types as well as making deposits. 

I've added sample screenshots for you:

You can check out here for more information with the new interface of QuickBooks Online.

Tag me anytime if you have other questions. I hope you're well today!