On the macbook I exported a successfully tested app from Xcode 11.4 and dropped the .ipa file in AppBox. Appbox then gives you a link.Then I emailed the link to myself, clicked the link in Safari on my iPhone 7, tapped Install Application and got ‘“dl.dropbox.com” would like to install “News”’. I tapped Install.
It created the News app on the phone, but when I tap, I get "Unable to Install “News” Please try again later.
The I tried Diawi. Same result as AppBox.