A hint here. If you cut out the disk on your bandsaw or bench saw or with your router, you will have a center point identified. Get a drill bit that will just fit through the threaded center of the floor flange. Insert it through the floor flange and position the point of the drill bit in the center point on the disk. This is important to minimize vibration.
Disks come with adhesive backing and without.
I buy plain-backed disks and just use a little rubber cement to adhere to the plywood. This way I can remove the disk when it gets pitched up and worn, with a little rubber cement thinner. Screw the assembly onto the radial arm saw. You can clamp a block of wood onto the table for use as a work rest. One item of caution here.