Continental philosophers and romantics such as Schopenhauer and others found that 'the will' is what I understand a transcendental element of human beings in a sea of infinite possibility. — Question

That's a muddled take on it, in my opinion. 'Will' is indeed associated with Schopenhauer, but I don't know if he would categorise 'will' as transcendental (anyone?)

As much as [Schopenhauer] opposes the traditional German Idealists in their metaphysical elevation of self-consciousness (which he regards as too intellectualistic), Schopenhauer philosophizes within the spirit of this tradition, for he believes that the supreme principle of the universe is likewise apprehensible through introspection, and that we can understand the world as various manifestations of this general principle. For Schopenhauer, this is not the principle of self-consciousness and rationally-infused will, but is rather what he simply calls “Will” — a mindless, aimless, non-rational impulse at the foundation of our instinctual drives, and at the foundational being of everything. Schopenhauer’s originality does not reside in his characterization of the world as Will, or as act — for we encounter this position in Fichte’s philosophy — but in the conception of Will as being devoid of rationality or intellect.

SEP

Kant's use of 'transcendental', on the other hand, is something like: that which gives rise to experience, or makes experience possible, which is not in itself an object of experience. By that Kant means faculties such as the categories of the understanding, the primary intuitions, and so on - it's a big list - without which experience itself could not be ordered or intelligible, but which are not themselves objects of experience, so are in that sense 'transcendental'.

'"I entitle transcendental all knowledge which is occupied not so much with objects as with the mode of our knowledge of objects in so far as this mode of knowledge is to be possible a priori". [A295/B352]

Although it is also true that he employed the term in a variety of ways, some of which appear to conflict with each other. But that is the general gist.