So I want to set the rotate canvas shortcut similar to what I have on Photoshop which is, press R and use the stylus to rotate. I tried changing that in the settings but it doesnt seem to work. Can someone guide me how to get it done the way I want to?

You need Settings -> Configure Krita -> Canvas Input Settings

As default, R+Left Button (or stylus) is used for Select Multiple Layer Mode in the Select Layer group but you can change that to Shift+R+Left Button to free up R+Left Button for other use.

In the Rotate Canvas group, you can add a shortcut of the Mouse Button type as R+Left Button to give Rotate Canvas, or change the existing one which is Shift+Space+Left Button as default.

Thanks a lot!