Does the wiki support PostgreSQL databases for storing wiki content?
PostgreSQL is a free open source database which used to be kind of the big daddy of MySQL, providing more functionality but generally regarded as a bit more heavyweight, harder to install and so less popular. PHP integrates just as well with PostgreSQL, and PostgreSQL is available on a lot web hosting services.
Install PostgreSQL on your webserver, or check if your web host provides you with PostgreSQL databases before attempting to install such a wiki. You may prefer a wiki which uses Text Files for storage (although many web hosts do not allow file writing operations, so you must also check this)