Do you mean the tags in this example?
If so, that is part of standard Q2A functionality, not a plugin. If you don't have that on your site you may need to tick some of the boxes at the bottom of the Admin > Posting page.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.