Hello!
My first aqara device was actually not 1 but 2:
Aqara U200 Lite
M100 Hub for the above doorlock
Installing was - not by Aqara’s fault - quite a pain. As I, in part, replaced my old Verisure LockGuard system the Aqara kit unfortunately didn’t contain all required tools to properly support the - remnant - LockGuard EU cilinder. I’d only removed the big LockGuard cilinder and left the cilinder installed, for now. This cilinder has a fixed key that is inremovable. Only a small rectangle protrudes.
So lo and behold I tore apart the entire LockGuard to only migrate the small green key holder. Which fortunately fit in one of the Aqara supplied adapters. Did require to screw in about 3 tiny screws as else the green thingy kept spinning inside the key adapter. Just took a couple of hours as I had to keep the volume down in the middle of the night.
@moderators: if you need a photo of said green part let me know.