Create a dynamic payment amount for online checkout

Ok, so I love the idea of using the checkout links. I have a few created:

This is an example of one. The way I WAS doing it was to pass a custom amount, name and email address to the payment form. Once they paid, it would email them a custom receipt on my letterhead with their name. For some folks, the square receipts alone are not good enough to be reimbursed for their HSA or FSA accounts, so I need to be able to send my own receipt.

I need to either be able to use the checkout links as above, and then have it create a record of the payment in my system (so I can send them the email with the receipt) OR figure out how to get this dang payments sdk to work (which it isn’t).

So, how can I make whichever is easiest happen? A for-dummies version, if you have one. The walkthrough for the new SDK isn’t dummy proof like the last one was, or I’d have it by now. I’m using Laravel.