ASP.NET snippets sample Authentication error Code: ResourceNotFound - asp.net-core

Question

I'm looking for ways to manage and monitor groups and activities that are happening during the meets in MS Teams. So I thought this might get me started: https://github.com/microsoftgraph/aspnet-snippets-sample
I did everything according to the guide, howewer when I try to login with my work account, it outputs this error:
fail: Microsoft.AspNetCore.Authentication.OpenIdConnect.OpenIdConnectHandler[17]
Exception occurred while processing message.
Status Code: NotFound
Microsoft.Graph.ServiceException: Code: ResourceNotFound
Message: Resource could not be discovered.
Inner error:
AdditionalData:
date: 2020-11-28T14:54:07
request-id: /*not sure you should see this*/
client-request-id: /*not sure you should see this*/
ClientRequestId: /*not sure you should see this*/
at Microsoft.Graph.HttpProvider.SendAsync(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationToken cancellationToken)
at Microsoft.Graph.BaseRequest.SendRequestAsync(Object serializableObject, CancellationToken cancellationToken, HttpCompletionOption completionOption)
at Microsoft.Graph.BaseRequest.SendAsync[T](Object serializableObject, CancellationToken cancellationToken, HttpCompletionOption completionOption)
at Microsoft.Graph.UserRequest.GetAsync(CancellationToken cancellationToken)
at SnippetsApp.Startup.<>c__DisplayClass4_0.<<ConfigureServices>b__3>d.MoveNext() in C:\Users\master\Documents\aspnet-snippets-sample-master\SnippetsApp\Startup.cs:line 62
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.Identity.Web.WebAppServiceCollectionExtensions.<>c__DisplayClass4_1.<<AddWebAppCallsProtectedWebApi>b__1>d.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at Microsoft.AspNetCore.Authentication.OpenIdConnect.OpenIdConnectHandler.RunAuthorizationCodeReceivedEventAsync(OpenIdConnectMessage authorizationResponse, ClaimsPrincipal user, AuthenticationProperties properties, JwtSecurityToken jwt)
at Microsoft.AspNetCore.Authentication.OpenIdConnect.OpenIdConnectHandler.HandleRemoteAuthenticateAsync()
It appears that this error usually happens when trying to use mail services when user has no mailbox created.
Did I miss something?
Edit: My user type in Azure Active Directory is member.

Answer 1

This issue has explained this error. You need to login with a Microsoft account(personal or work/school), not an invited account.
When sending an email as a user, the user needs to have a mailbox
associated with them.
Users without a license that includes Exchange Online, as well as
external users (e.g. invited users) will generally not have a mailbox
in the tenant, and thus would be unable to send emails.