Thanks for reaching out to us about this.
Spotify has recently changed the song limit. Now, you can download up to 10,000 songs on each of up to 5 different devices. You can read about this in the relevant support article here.
There is an existing idea in the Community which suggests that we lift the song limit altogether. If you are in favour of this, we suggest you head over there and vote for it.
Hope that clears things up!
Stay awesome 🙂