My apartment patio is covered, so I have some tall jacks that hold the corners, I stapled across the top, and at the bottom I used velcro ties to hold the net to the gate.

I have built a few standalone catios as well. I usually use goat wire as I’ve had some issues with chicken wire before, staple it to whatever frame I’m using, and then add an exterior aesthetic frame to the outside to help hold everything in place and to look much nicer.