Your device must be connected to the WiFi SOHO.
Swipe down from the top to activate the navigation panel. Tap the gear to open settings.
The relevant menu in this version of Android is called Connected Devices. That might not be the case on yours. Look for Cast in the description, or use the search box.
Choose Cast.
Tap the name in the list of available devices that matches the name of the meeting room you are in.
To disconnect, tap the device you are connected to …
… and select Disconnect.