How to create 100’s of sub folders in Sharepoint document library.

This can be achieved by Sharepoint PNP Powershell module.

PART 1 — Create & Configure App Registration in Azure.

This is required because your tenant restricts the default PnP app to read-only.

Step 1.1 — Create App Registration

Go to https://portal.azure.com

Go to Entra ID

Go to app registration

Create a new app registration and call it PnP-PowerShell module