Create App Catalog in SharePoint online
App Catalog: Make apps available to your organization and manage requests for apps. An app catalog is required to disable Store purchases for end users.
2. At the top of the page, choose Admin, SharePoint.
6. On the Add a document form, browse to your app for SharePoint package and choose the OK button. A property form for new items opens.
7. Fill out the form as needed and choose the Save button. The app for SharePoint is saved in the catalog.
9. Choose add an app, and on the Your Apps page, find the app. If there are too many to scroll through, you can enter any part of the app title (Instrumentation) into the search box.
10. When you find the app, choose the Details link beneath it, and then on the app details page that opens, choose Add It.
11. You are prompted to grant permissions to the app. Choose Trust It.
12. The Site Contents page opens and the app is listed. For a short time, a message below the title indicates that it is being added. When this message disappears, you can choose the app icon to launch the app. (You may need to refresh the page to make the message disappear.)
13. Exercise the app as described in the sample description above.