There are actually many different techniques for playing bass, which by the way is still my main instrument and I've been playing it since 1997

Many play with a plectrum, note that you may want a large, thick one.
Lemmy Kilmister used to play with a pick and also sometimes strumming the bass like it was an acoustic guitar.
Steve Harris hits the strings perpendicularly with the tip of of his fingers, and he purposely keeps his fingernails long-ish to add some "bite" to the sound.
Funk players often use some sort of thumbstyle technique, for which it doesn't matter how long your fingernails are.
There are many more possibilities, none right or wrong. It's all a matter of style and what you want to achieve.
For a beginner it's ok to start with a pick, and then develop your own style.