Yes.
I believe that the root user is automatically called
admin for this install. I think that there is an apt-get command which will let you set up an administrator's password, using the terminal. Or it can be done from the desktop software manager.
Look at the pages I refer to above and keep in mind that apt-get does not install a current version of Dokuwiki. The last time I looked it was several years out of date. I'd suggest that you follow the instructions for installing from the latest tarball, as described here:
https://www.dokuwiki.org/install:ubuntu?&#alternative_easier_custom_installation