How do you secure network racks to walls with metal studs?

Will be mounting a 10U hinged network rack to a wall which has metal studs in a office. What would be the best way to do this? I’ve been to multiple sites with plywood behind the rack. I don’t understand how this would help.

Let’s say I use a Middle Atlantic rack which has 16” spaced screw holes and the studs are 16”, would I need plywood? If the studs are 24”, would I then need plywood?

Is the plywood basically a way to grab on to the studs with racks that aren’t able to do so? Finally, what type of screws do I use for the studs?

Thank you.