I played piano for years before transitioning to bass guitar.
I'd tell you . . .
First, keyboard synth bass patches/ tones are often far bigger and thicker than bass guitar, so you often have to be careful they're not TOO big and overwhelm things, and . . .
Second, if you are playing bass guitar lines, play them authentically as a bass guitar would. If you are covering a tune that originally (and obviously) a key bass line, play that authentically.
Often, in a world of drum boxes, synths, and samplers, listen carefully to recordings and you notice the drummer had three legs and four arms, string parts that would require 12 Maestro Perlmanns to play, or horn and/or string parts way out of their normal ranges. Don't be that guy, unless these are original parts doing that sort of thing as effect or a centerpiece of the tune.
Depending on the stage load out, you can run this through your bass amp if need be, but generally they're better FRFR or run through the IEMs. Any of the QSC-style of powered monitors would shine at this.
As far as the actual playing, you'll simply have to practice if not a fluent keyboard player, in which case remember to never use your thumb on the black keys!