The complete list of commands I used before logstash-plugin install is
tar zxf logstash-5.2.2.tar.gz
cd logstash-5.2.2
bin/logstash-plugin install logstash-output-zabbix
I do recommend running bin/logstash-plugin from the logstash install's root directory, rather than from the bin subdirectory as the PATHs may be getting confused.
Not sure about the Maven output messages, but it does look like the install completed successfully. You'll know if you try it and it doesn't give an error message.