Reminder, this is a full featured payment system. There should never be a need to go to the payment provider after you've setup your account.
I'm adding some screenshots here to hopefully give a bit more detail about the capabilities of this payment module.
You can set the order statuses for various actions in the Addon Settings page.
And as normal, you setup the payment method with details from the payment provider. Note that you can have different locations for different payment methods. This could be very useful for MVE environments.
When an unregistered user goes to checkout, this is what they see:
Note that the fields are actually iFrames to squareup.com so the card data is never part of your site (PCI compliant). Once the Encrypt card button is pressed, squareup.com will send an encoded value for the card that will be used during checkout. The user will then see the page look like:
If they click "Reset card" it will take them back to where they started to re-enter the card data.
When the click the "Submit order" button, they see the normal checkout stuff. I.e. Errors come back in Error notifications and Success comes back to the summary page.
For a registered user who may have used your site a number of times, they will have a bit different view. I.e. they can easily just select the card they want to use and move quickly along. Cards are automatically stored for registered users. So if this user had 2 cards previously used on your site, they would first see:
If they click the Enter new card radio button, they would then be able to enter a new card (they can still select an existing card):
Clicking Encrypt card will (just like the unregistered user) have squareup.com send back an encrypted card code to be used during checkout. They would then see this new card info displayed in the list of card like:
And again, they can select any card they want. If they click the Reset card button then they will simply go back to the view they saw when they first entered the payment section of checkout.
The cool part is the admin area. This is where we've implemented the "real payment system" versus only supporting auth or capture and then expecting the merchant to go to the payment site to do any captures, refunds or voids. So in this example, the payment method was setup to just Authorize (not to capture). Hence on the orders.details page the admin would see:
Notice the buttons to either VOID the authorized payment or to Capture it. We specified that for an Authorize type of transaction that the order status should be Open. If we click VOID, then the transaction is voided at squareup.com and both buttons go away since there is no longer any valid options related to the payment.
If we click Capture payment, then the payment is captured at squareup.com and the order status is changed to what we specified for Captured payments (Processed in this case) and then a nice Refund button appears with the order total as the default amount. You can refund any amount up to the order total that you want.
Clicking the Refund payment button will tell squareup.com to refund the customer the amount specified and the order status will change to what we specified for Refund in the addon settings:
Hope this helps to clarify the extensive payment functionality this addon provides. Guess I should grab this page and put it into a document!