Issues with Royal Mail integration

Hello,

I’m getting an error when I tried to integrate Royal mail with Amazon. Error message is given below:

{“data”:null,“errorCode”:“INVALID_ARGUMENTS”,“errorMessage”:“One or more fields were invalid”,“errorReference”:null,“httpStatusCode”:400,“isSuccess”:false,“rateLimitPerSecond”:null,“userMessage”:“One or more fields were invalid”,“validationErrors”:[{“propertyName”:“mws_auth_token”,“errors”:[“The MwsAuthToken field is required.”]}]}

Any of you have come across this before?

Thanks