They’re just just update files; if you haven’t purchased them they wont work.
I didn’t know that…
If your looking for ‘free’ voice banks some have ‘lite’ versions. They’re of lesser quality and reduced capabilities like a trial version to demo. They do have some restrictions on publishing works with, so look at the terms and conditions if you do so. Not all voice banks have lite versions but there’s a good number of them to use.