This is actually the answer. In fact, this isn't just the answer to this question; this is how everyone should approach basslines. If it ain't hummable, it ain't groovin'.
A lot of folks here have said to keep it simple - play roots, etc. But if I'm completely honest - that track is really just, I dunno, lacking something. It's kind of slow, lacks some syncopation and rhythmic complexity (where's the hi hat? this groove seriously needs some hats)....it just feels like it's kind of in this weird limbo, this no-man's land. I'm honestly just not feelin' it as a rap groove or an R&B groove. But as I listen to it - I'm DEFINITELY feeling it as a soul groove.
But you, man, you can put the soul in this track. In fact, I say you need to. I think this is actually an old soul-style groove, and should be treated as such; let your bass be a voice, don't be afraid to fill and go high, and definitely do some call-and-response with the vocals rhythmically when you can. (If there's a chorus section with sung vocals, there's definitely a lot of room for creativity.)
It's worth noting that many of these genres call back to older styles of music as way of tribute; many R&B and rap songs sample the greatest grooves out there. Don't just try to think of this as a "rap" thing and go full snore on it. Look at it as a piece of music that's being sampled for your vocalists to throw some flow over. So yes, make it rhythmic, make it melodic, and bring the soul to the groove. I honestly think that if you just follow the roots and play what's already there that it'll just be amazingly boring unless you speed up the tempo (try 1.25 speed on the player, but it still needs some hi-hat).
Also, will you have someone playing drums with you? This is good to know. If so, maybe you two can work something out together. Good luck!
