According to the manufacturer, the hole must have a diameter of 232mm, so it will most likely not work with 220mm.

I have this cat flap and it won't work with 22cm.

In the instructions chapter 4.3 you will find the information that the diameter should be 232mm.
However, the sealing on the side will then be very tight, so these round plates may also have to be installed.
Apparently someone has found 229mm... In fact, this would correspond to the maximum width of the tunnel as far as I have roughly measured. But the glazing is still sealed and there are often larger unevennesses... so I'm afraid that's not really enough.

But if you're handy and have a Dremel, soldering iron, screws, print-to-print pin headers etc. lying around at home... with a direct loss of warranty and no guarantee of success, here is my short workaround... (of course, the glass thickness, distance of the cut-out to the frame etc. must all fit):
Unfortunately, we had also mistakenly prepared a 22cm hole in our new window with double glazing, so I quickly modified the cat flap and reassembled it in the window... IMPORTANT: the loop for the chip is embedded in the end area of the tunnel and connected to the electronics with cables through the tunnel. It is therefore not possible to simply cut off the upper corners of the tunnel along its entire length, as was previously the case with the version without the microchip. But with manual skill and practice with the tools mentioned, you can carefully cut off the part with the loop without damaging the cable, then cut off the upper corners of the remaining part of the tunnel that goes through the glass and then have to reattach the tunnel part with the loop in the inserted state (e.g. glue it with silicone) and connect it electrically... It's been a while... I had opened the housing back then and cut the cable to be able to make the connection with a plug after insertion. It wasn't really much fun.

It is recommended to have a glazier make a cut-out with a diameter of 229 mm in the desired position.

Note: Cut-outs cannot be made in double-glazed panes or safety glass. In such cases, a new pane must be used, whereby the cut-out has already been made by the glazier. The cut-out is then edge-reinforced and sealed.