Logic Monitor Collector Installation- Prompt for proxy address and port

Proxy Server is referring to a possible system or server(s) that provides you with access to the web. It would be something your company would be running within your environment and nothing at LogicMonitor. It's pretty rare these days and if you are not already aware of one, you are likely not using one.

I would guess the Collector asked for it because it wasn't able to reach the LogicMonitor portal. You should make sure that the server you have the collector on is able to reach your LogicMonitor portal at https://yourportal.logicmonitor.com in a browser. Also make sure that server meets the requirements per https://www.logicmonitor.com/support/collectors/collector-installation/installing-collectors#requirements-for-collector-servers 

Also see https://www.logicmonitor.com/blog/my-collector-is-down-troubleshoot-in-6-steps

If you need to whitelist access to the LogicMonitor Portal, the details are at https://www.logicmonitor.com/support/about-logicmonitor/overview/logicmonitor-public-ip-addresses-dns-names

If you need more specific help or someone to look at your portal, I would suggest reaching out to LM support.