>>xenosp+Ev
I'd wager that they have a enterprise certificate to sign the iOS app with. Then it's a matter of sending the spy victims to a URL, installing the app and granting access to photos/ location/ whatever.
>>tomovo+Zx
It says the devices were unlocked then the device was connected. I would assume the device is in the custody of the Chinese authority at this point. Thus, they can just go into Settings and trust the cert.