That bracket won't work with the telocat vane. Its made for the little red flag vane in the photo.
It should work fine. I believe there's a hole in the middle of the black plastic bracket that comes with the Telocat that allows you to screw the Telocat bracket to the furler adapter. It's somewhat convoluted, but it works. I've been using the Telocat for decades on a H18 with furler by using those parts.
And don't fold or crease the flag. Its plastic or mylar or something and once crinkled it will stay that way.
Those cheap red flags are basically useless in any wind over about 15mph- they will just flutter. Go with the Telocat. They're a little more expensive, but they're more sensitive, more durable, and all in all a much better wind indicator.