In order to connect your JIRA to Subject7, click on Administration menu and select Ticketing System submenu.
Ticketing System submenu launches the following screen where you can add your JIRA credentials. This is specific to each user in the account and not an account-wide settings. Provide your username, password (API Token), and URL of your JIRA system and click Save. You can use Test Authorization link to make sure your credentials are correct and Subject7 can connect to your JIRA successfully.
Now, Subject7 is connected to JIRA, and you can create tickets through Subject7.