MS Graph API Issue: "Error getting user's inbox: The mailbox is either inactive, soft-deleted, or is hosted on-premise."

I got "Error getting user's inbox: The mailbox is either inactive, soft-deleted, or is hosted on-premise." when I tried to follow this tutorial Build .NET apps with Microsoft Graph - Microsoft Graph | Microsoft Learn to list my inbox. I found out that the culprit was that my MS account was a personal one. In that case, to use Graph API to handle my account, I needed to choose "Accounts in any organizational directory ... and personal Microsoft accounts" in Step 4 of this page Build .NET apps with Microsoft Graph - Microsoft Graph | Microsoft Learn. I would have another issue if I chose "Personal Microsoft accounts only."

Supported Account Types