How to automatically share your screen with a group of users?

Question

teamviewer

I am looking for the simplest program with functionality that allows you to show your screen to a group (2-15) people in one local network. Without entering passwords, choosing people. And just clicked on the button (or hot-key) and automatically the screen was displayed on all other computers. And everyone had that opportunity.
I assume that on all computers the program that sits in the tray was initially installed, configured and running. Tell me plz.
Urgently. Who will prompt today the decision - I will pay!