In your inbox you have an overview of each ad, as well as each applicant for that specific ad.
And to send a message to several applicants, you just select the rental property that applies.
When you have done that, you can see the requests that are available. And you have a box where you can tick each person you would like to send this message to. It will be sent as an individual message for everyone, no chat group will be started.
The message you send can be free text or a prescribed "standard message".