Onlyoffice Plugin installation fix - all server plugin installed but need check why not work

I need someone help me to install an onlyoffice plugin externallistener so as to make the sample file workable.

youtube video: https://www.youtube.com/watch?v=n_s5Tg6_ov0

Plugin location
https://github.com/ONLYOFFICE/sdkjs-plugins
plugin external listener

Instruction on plugin install
https://helpcenter.onlyoffice.com/installation/docs-add-plugin.aspx

I have the document server installed and plugin also copied to the required folder as per above instruction. But the sample and plugin didn't show up and do not work.

I need someone who have experience to help me to check on error of it.