I took it from Microsoft Hardware website. It was available there at the moment. I'm not a newbie, btw.
Now, I've bought Sculpt Comfort Mouse Bluetooth, and it is successfully recognized by Microsoft Mouse and Keyboard Center. But the keyboard still isn't recognized.
You did not post your hardware specs and computer make and model so I assumed that you were. Sorry I made that assumption.
I have tried to download a 2.3 version from every link on the hardware website and cannot even see a download link for a 2.3 version. The latest I see on any page is 2.2. Please post a direct link to the page where you have found this 2.3 version.
Also, please post a screenshot of Device Manager showing all your keyboard and mouse devices.
Also, please post a screenshot of Microsoft Mouse and Keyboard Center and what it is displaying for your mouse and also for your keyboard.
Thanks.