Firefox .xpi file as extension for setting up Copper CoAP plugin on Firefox

[ameerhazo]

Hello everybody, I'm trying to set up Copper on Firefox version 53.0.3 and I am aware that the extension/plugin is not available anymore for Firefox 56+. I followed the instructions on how to set it up and I'm stuck at creating the text file [email protected] in the extensions directory of my Firefox profile. I noticed that the extensions file should be an .xpi file and I read that such a file needs to be verified in order to work (I'm not sure). Any help is greatly appreciated. Thank you and have a nice day.