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.
The sturdiness was an issue because my cats could bend it easily. Also the smaller gauge of the wire meant that they were chewing on it at times.
My biggest issue is that my boy got his paw stuck after reaching through to try and get a bug or something and hurt himself pretty bad after freaking out.
Goat wire is typically higher gauge, sturdier, and the holes are bigger but definitely not big enough to escape through.