The core Revive Adserver project is completely free and open source - we do not sell any plugins "here" on any of the official Revive Adserver websites.
I'm not 100% clear what you want to do - in your first post, you simply asked if you should buy some plugins for "sign-up / login / advertiser / publisher feature", and I assumed that you meant you wanted a "self-service" approach, where people could sign up and buy/sell advertising space.
If that's correct, then yes, you either need to make that yourself, or obtain (buy or otherwise) a plugin from somewhere else to do this. "Self-service" is not a feature of the core, free, Revive Adserver project.
HTH.
