In order to use Filebeat modules you need to send logs to Elasticsearch. Modules use the parsing capabilities of Ingest. In your case you are sending to Logstash instead of Elasticsearch, so parsing cannot be done.
If possible try sending your logs to ES. Otherwise, you can try converting the pipeline provided by the FB module using our conversion tool. https://www.elastic.co/guide/en/logstash/6.3/filebeat-modules.html