Wicca did not exist during the crusades. It was invented during the 20th century and is an amalgamation of (supposedly) pre-Christian pagan beliefs. One of Wicca's core beliefs is that witches were not satanic: they were practitioners of pre-Christian religions, so traditions were carried through time and persecution but not necessarily written down.

Wicca has (to my knowledge) no codified religious texts. There are certainly widely-accepted modern works that define Wicca's origin and beliefs, but none of them claim literal ancient provenance for the literature itself. Rather, they are believed to be snippets of surviving rituals and beliefs.

That being said, religion doesn't require a text, and certainly not an ancient one. Scientology is a good example of a modern religion with a definite modern text at its core (business/scam practices aside, Scientology is definitely a religion). Voodoo has no religious text at all.

The Wicca religion was invented in the first half of the 20th century by Gerald Gardner. Like many new religious movements especially in the neopagan direction it utilizes something called 'invented tradition'. This means the claim to date back and be in the direct tradition line of a much older/ancient tradition (prisca theologia) so as to appear more authentic and legitimate.

Gardner claimed in his own writings that he was initiated by an already existing, unnamed coven, and he thus merely made public the already existing teachings (dating back to the middle ages and even ancient times). Compare this to e.g. Carlos Castaneda's and Michael Harner's claims to have been initiated by mysterious, ancient indigenious shamans to become very popular western master shamans and leader of their own religious followings.