Publish ionic iOS App on BlackBerry UEM

Hello Friends,

i’m new in ionic and developed an small App for our Company.
Now the App is Beta tested and we want to Publish the App with our Blackberry UEM Server.
We don’t have any problems with publishing an Android App (.apk) with the Server.
But we also tried it with an iOS App (.ipa) File.
The Upload to the UEM Server did not make any Problems.
But if any User want to install the App, it only shows an white App Icon (not ionic default icon) and the App did not start.
The .ipa File was created with xcode 10 on an Mac.
I have an Apple Developer Account activated.
What did i need to do to successful publish an iOS App with Blackberry UEM?
It’s not planned to Upload the App to the Apple Store.

Best Wishes
flo.riano