Adding Categories only as admin

Hi,
I am trying to build an Web2.0-Service with a wordpress installation. For this I wanted to use the category tagging plugin (https://sw-guide.de/wordpress/category-tagging-plugin). But as it seems it is only allowed to add categories as an admin, no rights for moderators or users with less rights.

The problem so is, not all(only me) of my users will get enough rights to use the tagging function.

Is there any way to solve this? or how could registered user add tags to post made on my blog?

thx sebastian kurt