Once Jira Cloud for Intercom is installed any Intercom team member can add the app to his own Intercom Inbox.
To add the app to Inbox, open up Inbox and select Customize in the top right corner of the sidebar on the right.
After that click Add more and select Jira Cloud from the list of apps. You can optionally reorder your cards the way you like them to appear in your Inbox and then complete the process by clicking Done in the top right corner.
This is the app's home screen. By default you will be able the create new Jira issues by clicking on Create a new issue. Installing the companion Jira app will enable a bunch of additional features, such as linking Jira issues to Intercom conversations and seeing linked Jira issues in Intercom. Additionally, you will be able to comment issues directly from Intercom.
If you would like to find out more about the linking and unlinking feature please refer to the Jira app documentation.