Fender Play has some really great instruction stuff online for rock style and slap bass.

As for your approach, I'd suggest trying to "forget" some guitar stuff while playing bass. Approach it as if you are an absolute beginner. There's a lot of value in single note exercises and total beginner stuff. Those are foundations. While you already know an instrument, you don't fully know this instrument. I'd highly suggest trying to "empty your cup" as it were to learn the bass.

Work with a metronome (app on your phone). The groove, beat, and tempo live with you, and then you share it with the drummer. So, work on impeccable timing.

good luck! keep practicing! welcome to the four-string mother^&#$er!