Activating Activities Kit for Workflow Platform 2013
When the installation process is complete, go to “Application Management” –> “Manage web applications”
Select desired web application (usually it's Sharepoint - 80 or Sharepoint - 443) and press “Manage Features” button.
And activate the feature.
If you have a non-English installation of SharePoint, you may have to copy to copy VirtoWorkflow.ACTIONS from [SP HiVE]\TEMPLATE\1033\Workflow to [SP HiVE]\TEMPLATE\"YOUR LCID"\Workflow.
When the installation process is complete, go to site where you will to install Virto Workflow Activity, then go to “Site Settings”.
Select “Manage site features”, then activate “Virto Software Workflow Activities Kit for SharePoint 2013”