Also look at this: Also look at this:
https://www.dokuwiki.org/install:downloader
The package managers are always behind the current distros. The Fedora 26 appears to be two years behind. And they do not follow the standard installation setup but have a complex setup of their own. It's almost always advisable to use a standard dokuwiki install. If you do this, you should place the downloader in its own folder and give it a name other than dokuwiki, since the package manager has already taken that. And you should set seliniux to permissive, if that has not already been done:
setenforce 0. If that's not possible you will have to do that for the new install, assuming that it is set to strict. I've never done that so I can't be of any help there.