K2 for SharePoint App Deployment tool

Do not use the K2 for SharePoint app from the App store, use the app that corresponds to your version of K2.

The App Deployment tool can be used to deploy the K2 Five for SharePoint app to your App Catalog manually (assuming you did not select the option to run the App deployment automatically after installing K2).
The AppDeployment.exe tool is available in the K2 setup folder after installation:
"%ProgramFiles%\K2\Setup\AppDeployment.exe"

Run AppDeployment.exe to start the App deployment Wizard. For more details about using the tool, see the topic K2 for SharePoint App Registration and Activation

See the Adding the App to Multiple App Catalogs and Add the App to Multiple K2 Servers topics in the K2 Five User Guide for more information.
You may get the following error when you try to redeploy the app to SharePoint:

The provided App differs from another App with the same version and product ID

To solve this issue in case you want to redeploy the app, you can clear the SharePoint recycle bin by following the steps in this article: SharePoint 2013 App Development - Troubleshooting: Provided App differs from another app with the same version and product ID