Problem with accessing the Outlook mail inbox of a Microsoft account

I have a problem with accessing the Outlook mail inbox of a Microsoft account. It all begins with logging in, successfully, and getting an access token or a refresh token. Basically, when I call ConfidentialClientApplication.AcquireTokenByAuthorizationCodeAsync when logging into my Microsoft account, my app does not want to use the same authorization code twice, since it believes that that I am using an expired authorization code.

Here is my "OnTokenResponseReceived" function, where I am calling ConfidentialClientApplication.AcquireTokenByAuthorizationCodeAsync:

        public async Task OnTokenResponseReceived(TokenResponseReceivedContext context)
        {
            _logger.LogInformation("in public async Task OnTokenResponseReceived(TokenResponseReceivedContext context)");

            _logger.LogInformation("code = " + code);

            string userId = context.Ticket.Principal.FindFirst(ClaimTypes.NameIdentifier).Value;
            Microsoft.Identity.Client.TokenCache tokenCache = new SessionTokenCache(userId, context.HttpContext).GetMsalCacheInstance();
            Microsoft.Identity.Client.ClientCredential clientCred = new Microsoft.Identity.Client.ClientCredential(_azuread.ClientSecret);
            ConfidentialClientApplication cca = new ConfidentialClientApplication(_azuread.ClientId,
                string.Format(CultureInfo.InvariantCulture, _azuread.AadInstance, _azuread.Tenant, "/v2.0"),
                _oauth2.RedirectUri,
                clientCred,
                tokenCache,
                null);

            try
            {
                Microsoft.Identity.Client.AuthenticationResult result = await cca.AcquireTokenByAuthorizationCodeAsync(code, _oauth2.AppScopes.Split(' '));
            }
            catch
            {
                /*
                var ccaUsersGetEnumerator = cca.Users.GetEnumerator();
                if (ccaUsersGetEnumerator.MoveNext())
                {
                    Microsoft.Identity.Client.AuthenticationResult result = await cca.AcquireTokenSilentAsync(_oauth2.AppScopes.Split(' '), ccaUsersGetEnumerator.Current);
                }
                */
                throw;
            }
            finally
            {
            };
        }

ConfidentialClientApplication.AcquireTokenByAuthorizationCodeAsync fails. Thus, the catch block is triggered, and the throw statement runs. Then, the event function "OnRemoteFailure" runs. Here is my implementation of "OnRemoteFailure":

        private Task OnRemoteFailure(FailureContext context)
        {
            context.HandleResponse();
            context.Response.Redirect("/Home/Error?message=" + context.Failure.Message);
            return Task.FromResult(0);
        }

My FailureContext.Failure.Message says the following:

"AADSTS70000: The provided value for the 'code' parameter is not valid. The code has expired.\r\nTrace ID: 8c9eac2b-d2dd-4a46-a53d-01ed43ba0300\r\nCorrelation ID: af04f562-9287-4d48-aaef-bab08bfa5b48\r\nTimestamp: 2017-08-03 05:55:30Z"

Whereas, if I am logging into my work or school account, my app believes that it should get an access token with the authorization code that was provided. Thus, ConfidentialClientApplication.AcquireTokenByAuthorizationCodeAsync succeeds. I am able to access the Outlook mail inbox of a work or school account.

In the case of logging in with my Microsoft account, I found out after researching online that instead of getting an access token, I have to get a refresh token, but the problem is that the ConfidentialClientApplication that I initialized does not believe that it has a user. I was thinking that I needed to store the refresh token in the cache for the specific user. (Notice that in the "catch" block of my "OnTokenResponseReceived" function, I commented out the part where I tried to get the refresh token, since I wanted to show you that I ran into the error of the expired authorization code, first. However, I could not get the refresh token since ConfidentialClientApplication.Users.Count is 0.) Here is a screenshot of the ConfidentialClientApplication.Users.Count being 0.

Screenshot 1

If I am using an expired authorization code in the first place, how would I get a refresh token?

Here is my GitHub repository.

Sorry for creating another discussion about a similar problem to the problem that I resolved, today. Thanks!