filter/flange install

Just bought my carbon filter.
Did not expect to have to drill the flange onto the filter like this, I've never drilled into metal before. So before I fuck up I have one major question that wasn't really answered in the instructional video on can filter's website.
Do I drill through the gasket tape on the flange? should I try to get the screws on the inside or outside of that?

Is the gasket tape sticky on both sides or just one? If it's just one, I'd position the flange on top of the filter, mark the holes with a sharpie, remove flange, drill, attach gasket tape to underside of flange, poke screws through the tape and thread into the drilled holes.

If it's double-sided tape, that would explain why their instructions sound like the flange should be secured to the filter before drilling. It would be hard to drill the holes and position a sticky flange just right so all the holes line up. If it's double sided, they're securing the flange first, then drilling the holes through the tape. The holes in the flange acting like a drill guide. The double-sided tape keeping everything in place.

If you like that second option but it's not double-sided tape, you can use painter's tape around the circumference of the flange to secure it to the filter while drilling/screwing. Remove the painter's tape when done.

You shouldn't have to over-think it too much.

Yeah I was over thinking it. To anybody in the future that finds this thread in a google search-
It was single sided gasket tape, I put it as close to the outside edge as I could, I did NOT do a stellar job at that, but I did a good enough job.
I used the extra couple inches of gasket tape, I cut them into small pieces and put them in the spots around the edge where I had messed up the most, just in case. I don't think it made a difference.

after putting the gasket tape on the flange I marked where I was going to drill on both sides with a sharpie. I aimed for just inside the gasket tape.
Did not pre-drill any holes, just put the flange on the filter and drilled. It worked fine. The seal is perfect