Pre-install question, can clients pay without logging in?

Yes, clients can pay without ever logging in. Although the client information is tied to a WP User record, you are not required to actually provide any access to the client.

In other words, when you create a new client, a WP user will be created, but no email will be sent about it. So the client won’t even know they have a login, much less what the credentials are, unless you tell them. You could even go one step further and disable the user from being able to log in, if you want. Unless you are using our Client Area extension, the user record is only used as a place to save the client’s information.

From the client’s perspective the workflow stays the same… they get an invoice by email (when you send it), they click a link to view the invoice, and from there they can pay it. No login required.