When I tried to sign in to Skype on my Xbox One, it shows this error message:
Ask your parent to change this setting for you
You can't Xbox Live Gold is required to use Skype for Xbox One because of how your account is set up.
Your parent can change this for you in your privacy settings.
(This is exactly how the error message appeared, with the weird grammar)
I have Xbox Live Gold and not using a child's account (is that a thing?), and I can sign in to Skype just fine on my PC and phone.