Mains powered smoke alarms must be installed by a qualified electrician.
Battery or lithium powered smoke alarms can be installed by pretty much anyone however the more experience someone has the better they are at installing them, especially if they need to be interconnected wirelessly.
Electricians can of course install both mains powered and lithium/battery powered smoke alarms, however they may not track and record asset details and testing history to the same extent as a smoke alarm compliance company.
We would always recommend property managers use a smoke alarm servicing or compliance company. Especially if you deal with many properties because the smoke alarm compliance business will track and record your whole rent roll with meticulous detail.
Some smoke alarm compliance companies employ their own electricians. Check Systems works with a number of alliance partners that conduct electrical work under a quality agreement.