There are multiple ways in which the app can be installed

By searching on the Marketplace from within Jira 

1. As a Jira administrator, click on icon at the top right corner, just beside your Jira profile picture. 

2. Click on Apps option.

3. Now select the Find new add-ons menu item and enter Roadmap Portal in the Search box.

4. In the resulting search, select Roadmap Portal and click on the Try app button. Clicking on it will give you a Free 30-day evaluation version.

5. The software will now be installed and the license key will be automatically added to activate it. 

By clicking on the “Try it free” or "Buy it now" button on the app profile page on the Atlassian Marketplace

1. In the https://marketplace.atlassian.com/vendors/1211499/amoeboids-technologies-pvt-ltd, click on the Try it free or Buy it now button.

2. This will take you to https://my.atlassian.com where you can either enter your User ID/password or create a new account. This will give you a free 30-day evaluation version or let you buy licenses.

3. The app will now be available for download and the license key will be available to add