This process can take a long time, depending on the length of the list and how many levels it's separated into - longer lists may take a couple of minutes.
Don't refresh the page after you have pressed "Scrape!".
You will be redirected to the list once it has been scraped - just leave the tab open in the background.
If you have to be logged into Memrise to view the list, the scraper will not work! (the list must be set to public)
If you want more such as audio and other columns, and you use Anki, you may be interested in this Anki extension.
If the process takes more than 100 seconds, Cloudflare will cut the connection, so you have refresh the page once the error is displayed.
I still haven't made a progress bar so there's no way to tell how much is left - for now if you close the tab after starting by accident or in frustration and come back later the list will be cached for you.
Some lists just don't work and I can't work out why, eventually I will compile a list and give feedback to the author of the script.