After you enable Spotify in Settings → Services, Sleep as Android will connect to your Spotify account to be able to download information about your saved albums and playlists. Then you can set up one of those as your alarm’s ringtone or lullabies. See Ringtone.
Where can I try the spotify app? I want to download music there.
Good to save Spotify music as alarm’s ringtone. I use the songs downloads with my subscription. Then I save the songs via the Spotify Song Downloader from AudFree. I get the lossless music files and play them offline anytime.
Yes, by doing the way you said, Spotify Premium users can set Spotify Sleep as Android and set Spotify music as Ringtone easily.
But things could be difficult for free Spotify users. There is no way to do this for them. To set Spotify music as Android Ringtone, they need to use a powerful Spotify Downloader to download Spotify playlists and albums as local files and upload them to Android for creating as Ringtone.
To wake up with your favorite music tracks is a very perfect thing. You could choose to set Spotify song as alarm using Google Clock App and SpotOn. However, the feature is only available for those premium subscribers.
It doesn’t matter. Spotify Music Converter Mac can enable you to set any Spotify track as an alarm with ease. You can download Spotify music and then choose it as an alarm ringtone on your phone.
I agree with you ! I am using the Spotify free account so I have no idea to use the Google Clock App and SpotOn to setting the alarm,but I found another Spotify Music Converter-Tunelf which could solved my problem.it could convert the Spotify music to other format to set Spotify as Alarm easily.
I discovered a post that includes lots of ways to set Spotify as an alarm. It’s much easier and clear to follow the steps. And the most important thing is to download Spotify music offline by the Spotify music downloader because it lets you use Spotify on any device with no limit.
You can go to Spotify official site to download the app on your computer. If you want to use Spotify on mobile devices, just go to the app store on your phone, and search to download it.
By the way, you can try AudBite Spotify Music Converter to help you download Spotify music without Premium account. Spotify officially only allows Premium users to download most of the music. Good luck!
Hope this answer will help you. 
Hi,
I am having issues connecting Spotify with Sleep as Android.
When I select the toggle inside SA app and confirm the app integration on Spotify it just stays on spotify confirmation page, as if the confirm button was never pressed. There is no redirection to the SA app happening.
After the first time it just gives a white page, with no consent form.
SA app already has consent which I can check inside my Spotify acount.
There seems to be an issue with browser redirecting back to the app.
I have tried removing SA app inside Spotify account and redo the process many times.
SA never gets the Authorization code back from Spotify consent form.
Using brave browser. I also tried opening the URL inside Edge browser but getting the same result: the app never opens back after giving consent.