How do you hardwire the eufy battery video doorbell (Dual power) in the UK?

I have just purchased a eufy battery video doorbell which can be dual powered to existing mains doorbells and chimes. It says you need to have between 8v and 24v ac to run. I have a deta 3500 doorbell already that says it uses 240v. How can I wire my new eufy video doorbell to this to constantly power? Any ideas would be much appreciated. Thanks.

I have deta mechanical door bell chime as well, I tried to wire up the eufy battery doorbell using the existing door bell wiring, it sounds the chime on the deta once but then doesn’t work afterwards, does it have enough voltage to power the doorbell, can anyone help?