She's not letting them play her music. She just doesn't care to bitch about it (shockingly). Trump has literally been threatened with numerous lawsuits by multiple artists for playing their music without permission. This is an awful attempt at dragging Demi.
Not really. It's an ABC advertisement for their coverage of the convention. ABC is owned by Disney, who also owns Hollywood Records, who owns Demi Lovato.
Basically she didn't have to give permission because her label can do whatever they want with their own songs.