Cannot get PowerBI Access token

Here's the error I get while trying to get the access token.

{
"error": "invalid_grant",
"error_description": "AADSTS70002: Error validating credentials. AADSTS50126: Invalid username or password\r\nTrace ID: a34fb8ab-1026-4120-9d50-623a848b1600\r\nCorrelation ID: cbe5596a-d438-4807-be82-36769aefafe7\r\nTimestamp: 2018-10-10 13:47:30Z",
"error_codes": [70002, 50126],
"timestamp": "2018-10-10 13:47:30Z",
"trace_id": "a34fb8ab-1026-4120-9d50-623a848b1600",
"correlation_id": "cbe5596a-d438-4807-be82-36769aefafe7"
}

I'm using ASP.NET Core to embed the power bi report.

Here's my code for reference:

private static async Task<OAuthResult> AuthenticateAsync()
        {
            var oauthEndpoint = new Uri(AuthorityUrl);

            using (var client = new HttpClient())
            {
                var result = await client.PostAsync(oauthEndpoint, new FormUrlEncodedContent(new[]
                {
            new KeyValuePair<string, string>("resource", ResourceUrl),
            new KeyValuePair<string, string>("client_id", ClientId),
            new KeyValuePair<string, string>("grant_type", "password"),
            new KeyValuePair<string, string>("username", Username),
            new KeyValuePair<string, string>("password", Password),
            new KeyValuePair<string, string>("scope", "openid"),
        }));

                var content = await result.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<OAuthResult>(content);
            }
        }

        class OAuthResult
        {
            [JsonProperty("token_type")]
            public string TokenType { get; set; }
            [JsonProperty("scope")]
            public string Scope { get; set; }
            [JsonProperty("experies_in")]
            public int ExpiresIn { get; set; }
            [JsonProperty("ext_experies_in")]
            public int ExtExpiresIn { get; set; }
            [JsonProperty("experies_on")]
            public int ExpiresOn { get; set; }
            [JsonProperty("not_before")]
            public int NotBefore { get; set; }
            [JsonProperty("resource")]
            public Uri Resource { get; set; }
            [JsonProperty("access_token")]
            public string AccessToken { get; set; }
            [JsonProperty("refresh_token")]
            public string RefreshToken { get; set; }
        }

I'm using the same username and password and the same client ID for my MVC application and I get the token.