Most android boxes (and some lesser-known phone brands) encounter issues streaming from more "formal" services, typically because the manufacturers don't opt to go for Google's Widevine DRM certification.
So you often either can't play these protected streams natively (as seems to be the case with the ITV Hub App), or you might be limited to running at a reduced resolution.
Third party streaming apps are really the main way to go here unless you're using a more upmarket device like a Fire Stick.