You are trying to install ShortPoint on SharePoint 2019 server and got below error while Adding ShortPoint App to your site:
Sorry, apps are turned off. If you know who runs the server, tell them to enable apps.
Reasons and Solutions
|Apps are not enabled in your farm||Make sure your have Apps enabled in your SharePoint 2019 farm.|
|Subscription service is not setup||The first and most probably problem would be the subscription service is not configured in your farm. Please follow our article's PART 1: Configure Subscription Settings Service Application to configure it.|
|App management service is not associated with your web application||Make sure App Management Service Application is associated with your web application where you want to add ShortPoint App.|
|App Url is not configured||Chances are you have not configured the App Urls. Please ensure you have given values to App Domain and App Prefix in your App Store settings.|
If after ensuring above solutions, you still have the same error, please register a ticket with ShortPoint in order to let our technicians analyze the problem.