I stayed there because of cancelled flight, a reseptionist on shift told me that United Airlines would sent it to my email. But it never happened.
Just ask the the hotel manager on shift for a copy of your reciept. They should be able to print or email a copy to you.
If you're at the hotel and paid at the hotel, ask them for a print out. If you booked your room on another site, you should have been emailed a receipt, upon booking. The hotel should still be able to provide you with a print out either way.
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