Downloading Spotify Tracks to play on another Spotify Client

[JD2020]

Hello All, 

I just installed an Android Head Unit in my car. I'm able to install the Spotify on the head unit. The Head unit connects to WiFi so I can download my playlist for offline listening. I do have Spotify Premium. One of the issues that I've encountered is that its super slow when downloading the playlist for offline listening on the head unit. Is there a way to grab the tracks by using a USB or SD Card for use on the head unit? 

Thanks