Explanation
Step 1 (E): Install the Azure File Sync agent on Server1
The Azure File Sync agent is a downloadable package that enables Windows Server to be synced with an Azure file share Step 2 (D): Register Server1.
Register Windows Server with Storage Sync Service
Registering your Windows Server with a Storage Sync Service establishes a trust relationship between your server (or cluster) and the Storage Sync Service.
Step 3 (C): Create a sync group and a cloud endpoint.
A sync group defines the sync topology for a set of files. Endpoints within a sync group are kept in sync with each other. A sync group must contain one cloud endpoint, which represents an Azure file share and one or more server endpoints. A server endpoint represents a path on registered server.
References: https://docs.microsoft.com/en-us/azure/storage/files/storage-sync-files-deployment-guide