If you're serious about making money with your music, you already know the importance of Spotify and it's playlists. In this era of music, it seems like all it takes is your song getting on RapCaviar to blow you up. Here are 5 curators who accept free submissions.
This is the first place I found that took submissions. WHPH is a curator with playlists on Spotify, Apple Music, Deezer, and Youtube. They have two playlists relevant to Hip Hop and their most followed playlist is Fashion Store Music with 5,300 followers.
IndieMono has a larger selection of hip hop/r+b playlist, with over 10. The submission process is quick and easy, you just need to upload your info along with the URI of the song and you're good to go. Their most popular playlist is Sad Songs with over 300k.
There are a good handful of urban playlists on SpinGrey like Hip Hop Bangers and Slow Jams. The IT'S LIT playlist has 27k followers. SpinGrey run by 4 Dutch dudes with backgrounds in architecture and at Heineken. In order to submit music, you need to email them, though.
Daily Playlists has a Spotify and Youtube playlists. They also have playlists for specific blogs such as Earmilk. Their most popular playlist, Hip Hop Daily, has1000 followers, apparently. You can submit to that here. Note that Daily Playlists charges for placement.
Finally, Soundplate has Spotify and Deezer playlists. They seem to have the largest number of hip hop and r+b playlists of all the curators I've listed. They also have a very useful tool in the Playlist Analyzer, which shows you the average BPM, key, duration, and also the amount of followers on any given playlist on Spotify, along with some other interesting stats. The Track Analyzer does the same, so you have a better idea of what tracks work for what playlist, which is real dope. You can find their playlists here. Submission is a breeze.
Btw if you are a curator instead of an artist, you should check out al these curators and submit your playlist to help it grow. Sky's the limit but you gotta grow wings to test it.