I have never rated anything free poorly before but...
This add-on is useless on Firefox on Ubuntu 18.04 LTS. I use this extension of Firefox on Windows with no issue. But with the Firefox in Ubuntu, I can't log in from the add-on because when I click on or tab to the password field, the log in window closes. The ONLY way to log in is to go to the LastPass website and log in. I would give this add on zero stars if I could.