The Ubiquity dashboard is for iptables logs collected from Ubiquiti Networks firewall devices. These devices usually send logs to Filebeat over the network via syslog.
If you have one of those devices, you need to use:
var.input: syslog
var.syslog_host: 0.0.0.0
var.syslog_port: 9001 # change this if needed
And then point your device to send Syslog to the right address so that it can reach Filebeat.