You should have something from the warning in the documentation on the module front page (that you will have to import them as categories or delete your current taxonomy data). I didn't realize that this module wouldn't access the old taxonomy for me and then couldn't uninstall as the category module and the taxonomy wrapper module were codependent.

"If you have existing taxonomy terms and vocabularies, or if you have
existing book nodes, you can import them as categories and containeris using
category_legacy. To do this, go to 'administer -> category legacy', and
follow the instructions on that page. It is recommended that you enable the
taxonomy and book wrappers before performing an import. Additionally, using
the taxonomy wrapper with existing taxonomy data is not recommended - either
import your existing taxonomy data first, disable the taxonomy wrapper, or
delete your site's taxonomy data. You are able to leave the book module
enabled, and continue to use your book data, if you wish (but as with
taxonomy, it is recommended that you disable book)."