Is the Review and Pay that's on the invoice that I send a client, should they be able to click and pay straight away or do they just open invoice and use

It's good to see you here in the QuickBooks Community, @RVPhotography.

I'd be delighted to provide insights about the Review and Pay button when sending an invoice to a client in QuickBooks Online.

When using 3rd-party apps like PayPal for online payments, clicking on the Review and Pay option will redirect you to a page where you can view your invoices and access instructions for payment. Moreover, if you're not using any of the 3rd party apps, you'll have to record those payments manually.

To learn more about it, please review this handy article: Create an invoice your customer can pay online.

Also, I'll share with you this article if you want to know more about accounting for customer payments: Record invoice payments in QuickBooks Online.

Let me know how else I can help you manage your customers by adding a comment below. I'm here to lend a helping hand. Keep safe always.