Your son: connect his device with computer,open iTunes ,copy UDID code and email to you.If you follow the instructions it's pretty straightforward. You create the app in your ITC account, upload a build, then distribute it via TestFlight instead of submitting it for review.
There used to be online services that you could use to distribute an .ipa over OTA - but I haven't used one for years, so I don't know if they still exist. You could try Googling it.
See 123.jpg，Go to Settings >> Summary >> Options，Check manually manage music and videos >> Apply，then try again.Thank you all, unfortunately I'm afraid to be a little special.
I think that OTA (which looks very good) is made for those who have an account for hosted builder.
I do not have a hosted builder account, I use a local mac
watesoft : you say "open iTunes and drag app file into music". open iTunes and drag app file into music, then install it on the device."
yes but why? I can't drag and drop into iTunes. Afraid to be I do not use the right path
View attachment 78873