@Sean, Thanks for posting in Q&A. Based on my researching, Microsoft Intune uses the Microsoft Store for Business and Education to manage and distribute apps to devices. If the app is published on the Apple App Store, it may not be automatically available in Intune.
To make the app available in Intune, you can ask the app developer to submit it to the Microsoft Store for Business and Education. Here is a link with more details.
Hope the above information can help.
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