I don't recommend this extension. There are many session managers. I've used about 10 or so over the years. This is probably the worst UI I've yet seen.

The main drop down window of this add-on is disorganized and un-intuitive.

Where does it save the backups? In the preferences, it states, "Specify the folder to save the backup file. The save location is limited to the folder under browser download folder."

Does anyone have any idea what "the folder under browser download folder" means? I sure don't. I wonder if it's implicitly assuming the user is running Windows, but I really don't have the faintest idea. I looked everywhere I could think of, and did a search of my hard drive, but found nothing.

I'm very sorry I wasted time on this. Don't make the same mistake I did.