DUST TO DUST

BassBuzz on Youtube - He has a course you can buy too, but his YouTube videos are still incredibly helpful and well thought out. Here's a playlist where he goes over basics. And a bunch more. More channels I would suggest are: Become a Bassist, and TalkingBass. There are a bunch more, but I've mainly used these guys. I would suggest just digging until you find a video you like on YouTube in general, however.

Of course, a metronome is very important too for bass guitar.

If you'd like to learn the fretboard notes, there are multiple apps (though some charge subscriptions like FretPro but they're fairly cheap) and this website (musictheory.net) where you can drill them in for free. Along with that, here's a random note generator (random.bretpimentel) so after a while you can try to generate a note and find it on your fretboard.

For tabs and learning songs easier, while Ultimate Guitar is okay, I do find Songsterr to be easier due to having it set up so you can listen to the whole thing together. These are all community made tabs, so some might be off.

If you'd like to learn by ear there are various apps you can get for free. I just use Ultimate Ear Trainer, I believe it's on multiple operating systems.

And finally, StudyBass is a good website, too :) Reddit is also fun to lurk too if you can find the good comments and not people being snarky.