Hi J5P ,
It looks like there might be an issue on Brave's side regarding opening the popup using the link.
I tried it out on our test site, and I also couldn't get it to work.
They also have this support ticket about this same issue but he also couldn't get the link to work.
It looks like the trigger by class works but because Buttonizer loads in a bit later than Brave, Brave can't find the Buttonizer button class, and it will also not open on click.
Hopefully Brave will fix the link issue in their next update. If so, then you can also use that to open the popup instead.