The song is currently only available in the UK, USA, New Zealand, Ireland, Sweden, Australia, Denmark, Iceland, Czech Republic, Hungary, Poland, and Slovakia.
Madeon's debut album is coming out at the end of March, so if you can't listen to it now, you might be able to later this year.
The City will be on the deluxe version of his new album "Adventure".
For example, I used to be able to listen to "Finale" by Madeon, but now it's no longer available in the USA. It will probably be available again when the new album comes out later this year.
The reason is that the artist or their music label has decided to remove it from Spotify.
The availability of songs on Spotify is up to the artist and their music label.
Spotify has no control over what content is available.
Sometimes it is only available in certain countries, while access is blocked to others.
Sometimes the album or song will be unavailable temporary, and come back again later.
You can find out more information here