After you install the add-on, to verify that the installation was successful, follow these steps:

1. Go to the Administration icon . Navigate to Add-ons > Manage Add-ons.

2. Under the User-Installed Add-ons, you should be able to see the JIRA Misc Workflow Extensions add-on as shown in the image below.
   
3. Verify that all the modules are enabled.

Your installation is successful!