HMRC recognition and Gift Aid
HMRC recognition is what lets you claim Gift Aid, and Scouts very strongly encourages Gift Aid on subscriptions (POR 5e.8.1.4). In England and Wales you don't need to be registered with the Charity Commission first. In Scotland you do need to be registered with OSCR: an unregistered Scottish Group isn't a charity and can't claim Gift Aid.
Once recognised, tick it in Settings with your HMRC reference. The Charity page then reminds you to tell HMRC when the Chair or Treasurer changes, and to claim Gift Aid within four years.