How to use a user token/refresh token when using the Google Calendar API with the .net library

Question

I have a Blazor App which has a calendar. I want to sync the event from the app calendar, to the users Google Calendar.

I am using the 'Authorization Code Flow'.

I have succeeded in getting the first two steps done of the flow which is:

1.Getting an Authorization Code.

2. Exchanging it for a token + refresh token.

I now want to use this token to insert an event into the calendar. I have not found a way to do this.

I did find this example which ALMOST does what I want it to do. However, it is meant for a Desktop Application, not a server to server scenario. The user has already given consent in steps 1 & 2, and now the server, at a later date, will use the token to insert into a new event.

var credentials = await GoogleWebAuthorizationBroker.AuthorizeAsync(
    new ClientSecrets { ClientId = clientId, ClientSecret = clientSecret },
    scopes, "[email protected]", CancellationToken.None, sqlServerDatabaseStore);

if(credentials.Token.IsExpired(SystemClock.Default))
{
   await  credentials.RefreshTokenAsync(CancellationToken.None);
}

var service = new CalendarService(new BaseClientService.Initializer()
{
    HttpClientInitializer = credentials
}
);

What I need is a way to create the "credentials" using the token, but I am not seeing how to do this.