Why is my device prompting to sign-in to iTunes when installing apps?

When pushing apps to devices via MDM, you may see a prompt from iOS asking you to sign-in to iTunes.

By default, App Store app licenses are assigned to individual user accounts (Apple IDs). As a result, iOS requires that valid credentials for a standard (personal) Apple ID are manually entered by a user in order to purchase the license and complete the installation of an App Store app on a device. This applies to free apps as well as apps deployed with MDM.

The only way to avoid this requirement is to use the Apple Volume Purchase Program (VPP) for obtaining and distributing app licenses to devices using MDM. We have written in-depth articles on the topic which can be found at the following links:

If you already have access to an Apple VPP account, this guide provides instructions on how to link VPP to MDM:

Note: if you already have a VPP account connected to SimpleMDM and are still being prompted to sign-in with an Apple ID when deploying apps, check to make sure that all apps in the Catalog are being deployed as VPP apps (rather than App Store apps) and verify that all apps have an adequate amount of VPP licenses available. If they do not, log in to your Apple portal and add more app licenses. Then, in SimpleMDM, go to Apps > VPP and click 'Sync with Apple' to pull the new licenses in. After that, restart your devices, reconnect them to WiFi, and push the app installation again via MDM.