All users are required your wikis Terms of Use before being able to logging in and using Confluence.
Features
Before logging the user into Confluence a page with your Terms of Use will be displayed. If the user denies the terms he will be redirected to the login page again. After accepting the user will be normally logged in and his agreement will be stored. He will have to accept the Terms of Use only if the administrator changes the terms.
Administrators can configure a custom title, usage hint and the terms of use itself in Confluence administration console. You can use HTML to format the usage hint and terms of use, like adding headlines, paragraphs, etc. Each time the terms are changed, all users will have to agree again upon login.
Installation
This is a type two plugin, please follow the installation instructions as given by Atlassian: Installation steps via Universal Plugin Manager