Amazon SNS AmazonSimpleNotificationServiceClient.Token

I am currently stuck on CreatePlatformEndpointRequest.Token with my Windows Store App. I am not sure where/how to get this token.

I already have my Package SID, Access Key ID, and Secret Access Key

my codes are AmazonSimpleNotificationServiceClient sns = new AmazonSimpleNotificationServiceClient("secret", "secret", RegionEndpoint.EUWest1);

d("creating platform endpoint request"); CreatePlatformEndpointRequest createPlatformEndpointRequest = new CreatePlatformEndpointRequest(); createPlatformEndpointRequest.PlatformApplicationArn = "arn:aws:sns:eu-west-1:XXXXXXXXXX:app/WNS/AmazonSNS"; createPlatformEndpointRequest.Token = "what token?";

d("endpoint result"); CreatePlatformEndpointResult createPlatformEndpointResult = await sns.CreatePlatformEndpointAsync(createPlatformEndpointRequest);

d("endpoint arn: " + createPlatformEndpointResult.EndpointArn);

I get the following error "Invalid parameter: Token Reason: Notification Channel URI is not valid"

that's of course of the token I used "what token?" How and where do I get the Token value?

Thanks in advance