Bought a Computer with FileVault ON. Help!

Ask Alice to comply with these instructions: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support.

They are not optional and both of you are likely to encounter annoyances of varying descriptions until she does.

She and you ought to be able to collaborate over the phone to ensure she followed those instructions and comply with any she may have missed. Stick with her on the phone until you mutually reach the end of What to do before you sell, give away, trade in, or recycle your Mac - Apple Support. The Mac must start up to a "Hello" language selection screen and no longer prompt you for any passwords you do not know.

Encountering a FileVault password request (even if you know what hers was) is a sign the Mac was not properly prepared for sale. FileVault is not strictly related to preparing a Mac for sale since the startup volume must be erased, thereby erasing the FV password.

Urbaneness wrote:

Pretty sure I'm done with Alice on this computer but just want confirmation and Alice the person is out of the picture now. I need a different answer.

You mean an incorrect one that won't help solve your problem or maybe make things worse? You will need to get that from someone else.