You need to implement a backup solution for App1 after the application is moved. What should you create first?

A Recovery Services vault is a logical container that stores the backup data for each protected resource, such as Azure VMs. When the backup job for a protected resource runs, it creates a recovery point inside the Recovery Services vault.
Scenario:
There are three application tiers, each with five virtual machines.
Move all the virtual machines for App1 to Azure.
Ensure that all the virtual machines for App1 are protected by backups.
Reference:
https://docs.microsoft.com/en-us/azure/backup/quick-backup-vm-portal