Trouble with media_player group

I followed this integration → media_player.group

but I am unable to validate config with an exact copy of the the yaml in the documentation. My code write now is simply:

media_player:
  - platform: group
    entities:
      - media_player.cuisine
      - media_player.salon

When checking the config file I get:

Platform error media_player.group - No module named ‘homeassistant.components.group.media_player’

Is there something I’m supposed to activate before using the group platform?

What version of home assistant? Media player groups were introduced in 2021.7.

That’s the reason, i’ll update and check back here if it was the problem. Currently on 2021.5.5