Well - you will be musical, or you won't be. First thing (and this is my own view - others will hate it) is throw away the tab. Hardly any popular songs were played using it and somebody sat down and created the tab using their ears. There is NO point learning scales and the ability to read tab or proper music on a stave, if your ears and brain don;t work musically.
If I have to play a bass part and they want it as per the recording everyone knows, then I listen and listen till I can hum the part. If I can hum it, I can play it. Often I don;t even know what key it's in - I can picture my fingers in my head and can sort of practice it without even holding the bass. I learn the rhythms. I learn the going ups and the going downs. I learned every song in my bands set with a recording when I joined, replacing the old bass player who couldn't play any more because he was ill. I had his voice and his bass in my left ear and the rest of the band in my right.
With popular music the bass patterns are often very similar, so it's fourths, fifth, octaves and sometimes thirds in the bass. I learn intuitively - I don't care if I play a note at fret 5 or somewhere else as long as it is the right note, and as I am a lazy player, my goal is to be able to play it without any wild up and down the necks. I use the bottom B more than many players and play higher up. There IS a small tonal shift, but it works fine for me. I cannot play tab and from what I see, lot5s of it is a bit suspect. I'd not play it like that.This is why I like sheet music because it tells you the pitch and rhythm and leaves how you play that Bb to you - play it wherever makes sense.
You also need to develop prediction you hear a few notes and know what the next one is. Very good practice in bass playing can come from old slow rock songs - find some old Gary Moore stuff. The guitar gets the crazy stuff and the bass plays solidly and logically. Try Still got the Blues for You - every bass phrase leads you to the next and it's not that hard to play, but playing along with it will show you if your musical brain works. There are bits that sort of play A-C-E, then the next note before anyone has played it - should leap into your head and scream ITS A D! the chords and the guitar and the voice mean there is no argument over what bass note comes next. I think prediction is the biggest skill to practice, because you hear what comes next - even in songs you have never ever heard before.
Forget tab, forget learning to read music - tune your ear first. Do the same with Michael jackson' Billie Jean. Once you work out the pattern the bass plays, it's a killer song, and again, far easier to play than you might think.
When I do transcriptions of songs for stage tracks. I record the original into cubase. I set up a tempo track so I get a 4 in the bar click and then I do one or two bars at a time in a loop. Trying to hear what the instrument I am copying is doing. My memory is less good than when I was younger. Back then I might have remembered four bars worth of notes, Now, it's less in complicated songs.
Play along with the Gary Moore song and see if you can follow that.