Can't play a song

[13412405]

I am trying to play a song from Ariana Grande, but it's keeps saying that the song is unvailable and that I have to import it if I have it on my deskstop. Why would let me add it to a playlist if it's unvailable and why this particular song and not the rest of the album?

Is this song unvailable in Canada, the country right next door?

What's the point of having a premium account if the songs you want to listen are unvailable ?

Can you help me? Thank you very much

[13412405]

Ok. So, I opened the Spotify app on my Iphone and the songs are playing on this device.

The weird part is when I try to play the song on my mac it start to play on my phone. 

I am not geek, so could someone explained me why it don't play on my mac when my phone is off?

Thanks