For issues related to the Microsoft Store and AppX provisioning on your Surface Pro for Business, as well as the need for ARM64 OS repair media for an in-place repair, it is recommended to contact Microsoft Support directly. They can assist with escalation to the appropriate engineering team for your specific needs, especially given the urgency due to clinical work requirements.
You can access the Surface Support Portal or the Surface Management Portal to create a service request and seek immediate assistance from Microsoft agents.
References: