...
The app is available at the Atlassian Marketplace. To install the add-on, log into your Jira as a system administrator and navigate to the "Find New Apps" tab of the Universal Plugin Manager (UPM) in the global administration. There you simply search for "SharePoint Connector for Jira" and make sure you selected "Cloud" in the "Hosting Options" dropdown. You can find the UPM via the menu entry "Find New Apps" or similar. For more details about managing apps please refer to the documentation provided by Atlassian.
...
To try or subscribe to an app, click the Free trial button next to the app ion in the Atlassian Marketplace.
If you don't terminate the trial within the trial period, a subscription for the app kicks in. Trials last for a month from the start of your next billing date. After starting a trial, you can stop it from the app administration page.
Although you can re-enable the trial within the original trial period, you can't try it again beyond the original trial period. At that point, you can only subscribe to the app from the Manage appsApps page.
If you'd like to cancel your subscription to an app, go to Settings > Manage apps from the Jira sidebar, then click Unsubscribe.
...