Hello and Welcome to Advanced Installer Forums,
You can place your custom actions wherever you need them on the Custom Actions page. Simply create one under Install. The custom action will execute, store it's value in one of the properties mentioned in my previous post. Another custom action will be launched or not depending on the value of these properties. To achieve this, use the Condition field on the custom action's property pane found to the right. Lower on the pane there is a Condition field that determines whether the custom action should be run or not.
Since you are new to Advanced Installer, I highly recommend you read all our tutorials
. Should you find this too time consuming, you can read simple
tutorials. These two are mandatory for understanding how to properly create an installer.