No installation is needed, as the BritBox app is already installed on the Elisa Premium Digibox (Netgem) and Elisa Viihde Plus, the Android TV-based application. Learn more about apps and app sign-in on the Elisa Viihde support page.
You sign in using your existing BritBox account, or you can sign up on the web and later sign in on these devices using your newly created account.