Hey @FlorineBeckers, welcome to the Community!
It looks like you've reached the 3,333 offline track limit set per device. You can have 3,333 tracks synced on 3 different devices at a time.
We hope that helps clear things up.
Hey there you,
Yeah, you! 😁
Welcome - we're glad you joined the Spotify Community!
While you here, let's have a fun game…