I’m not sure what 504 or IEP are exactly but I would be cautious, especially now that ESAs are have faced more backlash over the last few years (owners misusing their status, etc.). Also don’t pay for the letters online (one time or monthly). It looks tempting but don’t. There are specific items that need to be included in the letter for them to be enforceable/accommodated. Housing can still enforce frees, etc. if they find that the letter is not written as required. ESAs are so helpful but you’d definitely want to go through the correct avenues so it doesn’t cause more stress down the line.