I'm not the best person to answer this given I only watched the animated versions of Garo.

So basically, the live action series have a continuity, and the anime versions are all different from each other. I suggest you check out the Garo wikia which I linked in the post. It makes it pretty clear what fits in what.

The Garo franchise is indeed popular, but as a tokusatsu series. It's only in recent years that the creator started branching out with animated productions.