To deploy custom apps (e.g., in-house apps developed for an organization), an Apple Developer account is required to create and sign the app using an Enterprise Developer Program or standard Developer Program account. Once signed, the app can be distributed via MDM using Managed Distribution, but the account is the prerequisite for app creation. Managed Distribution (option B) facilitates deployment but assumes the app exists, requiring the developer account first. User acceptance (option C) may be needed for installation on non-supervised devices but isn't the core requirement. A VPN configuration (option D) is unrelated. The Apple Platform Deployment Guide specifies the need for an Apple Developer account for custom apps.