You can find your invoice receipt in the transaction log of your Carson Dashboard account. This way, you'd be able to save your receipt as PDF file or print it directly.
After you open the Transactions tab, you will see all your transactions listed on the transaction log. You can search through the transactions for the one you need. You can also filter them, either by date or the amount paid.
On the right-hand side, next to the transaction details, you can find the "Invoice" button. Clicking on it will lead you to a new tab where your invoice will be in .PDF format.