When sending and receiving messages from Amazon SQS, check that you have the correct security configuration for the action.
Note that the recommendation from AWS is to use an IAM Role instead of an IAM user.
In general, you need to grant a policy with SQS access.
At the moment, by default all IAM users with the policy AmazonSQSFullAccess/AdministratorAccess can send/read messages to/from the queue. Check the Amazon documentation for more information.
Otherwise, you will get the following error:
{"Id":"GXQueue1002","Type":1,"Description":"One or more errors occurred. (The security token included in the request is invalid.)The security token included in the request is invalid.Exception of type 'Amazon.Runtime.Internal.HttpErrorResponseException' was thrown."}