how to connect to Facebook Messenger from Linux

Is there a messenger application that I can install on Linux Mint that can receive messages from Facebook Messenger, without having to be a member of Facebook Messenger? I see a variety of add-ons on Firefox, but most of them say one needs a Facebook account.

I am currently using Mint 19.3 Cinnamon 64bit on a Lenovo Thinkcentre desktop.

I am starting from zero here: I have never used a messaging app, and have never had a Facebook account; the only reason this has come up is that a new employer likes Facebook and Messenger ...