Zip file disappeared after Airdrop to iPhone 5

Hi,

I have an old iPhone 5 that I want to use as a simple storage. I airdropped a (large) zip file from the "Files" app in iOS 13.7 to the iPhone 5 running iOS 10.3.4 and it went through successfully.

However, there doesn't seem to have a "Files" app on iOS 10.3.4 and I have no way of seeing the received file on iPhone 5. The zip file may have confidential information in it and I can't even delete it!

It is a bit amazing that a device without a file browser can become so popular :)