This plugin allows you to create an action commission for the affiliate who has signed up. So basically it is a replacement for the default signup bonus functionality which you can find in your merchant panel under Configuration -> Affiliate signup -> Signup commissions -> Signup Bonus.
To be able to use this plugin you need 'Action commissions' feature activated and an action commission created in one of your campaigns.
Consult the Action Commissions guide to activate the feature and create an action commission. Set the name of the commission to whatever you'd like your affiliates to see, remember the code of the created commission since you will need it in plugin configuration and make sure the "Save transaction also for zero orders (Total Cost = 0)" checkbox is checked. It is also important to remember that the commission must be set as a fixed value commission since there is no value from which a percentage commission could be calculated during signup.
Once you sorted out the Action Commissions you can activate the Action commission for signup plugin from your merchant panel Configuration -> Plugins section. Find the plugin and click Activate next to it. After it is activated find it at the top in the 'Currently active plugins' section and click the Configure button next to it to actually set it up.
Instead of yourCode in the 'After signup action code' field enter the code of the Action Commission which you have created and instead of CampaignID in the 'After signup action campaign ID' field use the actual ID of the campaign under which you've created your Action Commission. How to find the Campaign id.
Once you save the configuration, each new registered affiliate in your Post Affiliate Pro (Network) will receive the configured Action Commission.
Tip - if instead of giving this commission directly to the affiliate who has signed up you'd want to reward his parent who brought him in and for any reason you don't want to use the default functionality from Configuration -> Affiliate signup -> Signup commissions -> Referral commission you can set the Action Commission's commission settings to be $0 for 1st tier and for example $5 for 2nd tier. This way the commission will be generated only for the parent affiliate of the newly signed up affiliate.