Amazon Simple Notification Service (SNS) AWS Mobile SDK for Unity

Hi great people of Unity Community!

I've been stuck for a while trying to enable notifications for my Unity project. I'm not using Cognito, so this is how the code is currently implemented:

 AWSCredentials Credentials = new BasicAWSCredentials(key, secret);
 IAmazonSimpleNotificationService SnsClient = new AmazonSimpleNotificationServiceClient(Credentials, _snsRegion);
 
 GCM.Register((regId) => { 
     SnsClient.CreatePlatformEndpointAsync(
         new CreatePlatformEndpointRequest {
             Token = regId,
             PlatformApplicationArn = AndroidPlatformApplicationArn
         },
         (resultObject) => {
             if (resultObject.Exception == null) {
                 CreatePlatformEndpointResponse response = resultObject.Response;
                 _endpointArn = response.EndpointArn;
                 Subscribe();
             }
         }
     );}, GoogleConsoleProjectId);
 }
 
 private static void Subscribe() {
     SnsClient.SubscribeAsync(new SubscribeRequest(topicARN, "application", _endpointArn), Callback);
 }

This is the basics of the code I have right now, what am I missing?

Thanks in advance!