Hey Becca, well it is always advisable to have a single generic Apple ID for the company, if you or another admin does not have access to these credentials while renewing the APNS certificate, the user would have to re-enroll all the devices.
The Apple ID is mainly used to push apps from the store to the device, VPP can be used to push apps directly to the devices.
When admin tries to push an app without the VPP, the user would be prompted to enter the Apple ID to log into the App store, in such cases a personal ID or a company shared ID can be used.
Thanks and regards
Evalyn Paul
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