Many organizations are moving to a MDM server for both shared use and one to one iOS devices. If you plan on assigning organization-owned apps to those devices, you will need to be a member of Apple's Volume Purchase Program and purchase both zero cost and paid apps from the VPP store, selecting managed distribtuion as your license type. Organizations that had previously purchased VPP apps with redemption codes that were largely used for Apple Configurator-based deployments need to request migration as per the instructions in Apple's support article https://support.apple.com/en-us/HT202863.
If, after migration, apps appear as only numbers with "B2B" next to them and you do not have any enterprise-owned apps in your distribtuion list, the cause is likely that the app is no longer available in the (iOS/iTunes) App store.