Dokuwiki does not contain the contents of any wikis, with the exception of the documentation about the Dokuwiki software, of course. It's like the paper factory which does not hold the contents of all the magazines and books that are printed on the paper it makes.
If the site's previous manager does not have copies of the contents of his former wiki, the owner of the server on which the wiki was hosted may or may not have copies. Most likely, they will not.