This plugin comes with a feature that lets you associate a customer with a specific existing WordPress user.
The benefit of doing this is that, if your customer is logged in with that WordPress user account, they can go to the page on which you’ve placed the customer tracking form (block or shortcode) and immediately view all of their orders. There will be no need to enter their customer ID and/or email address.
All you need to do is first make sure that they have an existing WordPress user account and then go to the Customers page, click to edit the customer, and then choose the user you want from the Customer WP Username field.