So a writing doesn't become scripture until it is authenticated.
Not authenticated . . . actually written into Scripture.
The "Book of Enoch" is not, and was not Scripture, not before, not after Jude wrote his letter. The quote from Enoch is Scripture because Jude wrote it in his letter, not because it appears in the "Book of Enoch".
Paul wrote Scripture. But the Cretan poets were not Scripture. Paul quoted one, writing it into the Bible. But this says nothing whatsoever about the source material in any other respects. In that case, he's just saying, your own people know this about themselves.
Jude, quoting Enoch, isn't even neccesarily quoting from the "Book of Enoch". My thinking is that this quote from Enoch was known long before the pseudepigraphical "Book of Enoch" was written, what, a few centuries before Christ? Jude was quoting Enoch himself, not a false book that happens to contain the same quote. That's my thinking.
But no, it's not that a quote is authenticated, and that demonstrating a non-Bible only stance, rather, it's that a Bible writer writes it. God inspired them what to write, and those Words are from God, and even if the same words appear somewhere else, that does not mean that other words in that other thing are likewise words from God.
Much love!