As far as I can tell, the rules are vague on what accepting the curse means.
That alone makes this a DM-specific interpretation issue, and I'm not aware of any published rules that place any limits on or are more specific about the curse. If you want it to be impossible to embrace the curse without awareness of it, then that's how it is and no rules lawyer will have much basis to argue.
That said, I would suggest that a cursed person can embrace the curse without being properly aware of it. I would also imagine that doing so would lead the person to become aware of the curse, and while unaware of it they probably can't gain all the benefits of embracing it. Let's think about what the curse actually is:
- The person turns into a beast during each full moon, regardless of
what they want
- The curse naturally drives alignment towards evil (to prevent this,
the person needs to resist the curse)
I'm not sure that "embracing the curse" necessarily suggests embracing being a werewolf. After all, a person aware of and resisting the curse knows that they are a werewolf but rejects the evil nature and behavior that comes with the curse. They don't deny that they transform under a full moon, and even if the did deny it that wouldn't help them. Resisting the curse is more about preserving your existing alignment and not indulging/refusing to allow circumstances that lead to violent episodes.
If the curse nudges people towards evil behaviors, they can indulge those and become more evil. This does not require awareness of the transformations and violent outbursts-- it's more like the devil over their shoulders becomes more persistent and persuasive. And, as in the preceding paragraph, resisting the curse isn't about denying that you are a werewolf but rather about refusing to do things the curse leads you to want to do more than you did before.
If a person were cursed with lycanthropy, embraced their newfound predilections towards evil, but never became aware of the curse itself it's hard to imagine them developing much mastery of their shapechanging:
Some individuals see little point in fighting the curse and accept what they are. With time and experience, they learn to master their shapechanging ability [...]
Emphasis mine. The bolded section suggests that lycanthropes who embrace their curse don't automatically gain mastery over it, but rather it becomes possible for them to do so.
So I don't see any reason that accepting the curse requires a full understanding of its effects, and a person who indulges in more evil desires certainly isn't resisting the curse whether they're aware of it or not. But it's up to you if you want embracing the curse to specifically mean embracing being a werewolf or embracing the supernatural imposition of evil desires and urges which result from being a werewolf (and do not require awareness of being a werewolf to perceive).