I tried this with Firefox and the Chrome version. As report by others, this addon displays the lists down the page, one after the other in one big long list. It doesn't create swimlanes going horizontally across the page. Same behaviour in both webbrowsers. Maybe it is something in my trello setup that is affecting it but I have a pretty stock standard trello board. It is quite an old addon so maybe it isn't maintained.

I was able to use it by copying the swimmer emoji and clicking on the green icon. However while this does create a new swimlane, it only works for one single column. I tried several times and found no way to reproduce the columns of the first line on the new one. I guess it's doable, but it's too complicated and Trello doesn't seem to react properly. Might be interesting for people with more time/technical skills to make it work.

To enable addon you need to click on search bar on green addon icon.
Works fine!

Note: Please change the shortcut because overrides the screenshot shortcut. :)

Doesn't seem to work

My favorite trello addon. Also, mentioned a problem with Jeff and he fixed it immediately.

Thanks! I have been waiting for swimlanes in Trello for a long time! Extension works great.