Bought an iPhone 15 Pro Max and didn't get a receipt

Welcome!

Check your emails from Apple regarding the purchase. At least one will have a

link to an invoice. It looks like this on Mail in iOS:

Also, you are not addressing Apple here but rather other end users gathered for mutual help with tech issues.. We cannot act on your behalf.

You will have to contact them again and ask if they can send your receipt by mail, or if you can drop by and pick it up.