This site enables you to buy applications on the SharePoint store or upload applications from the local server to SharePoint Online.
How does it work?
1. Login on the SharePoint admin center page
2. Click on the apps hyperlink button on the left pane
3. Click on the App Catalog hyperlink
4. Select “Create a new app catalog site” and click the OK button
5. Enter your information for the App Catalog site. Click OK
6. Site creation should take around three minutes
7. After the App Catalog is created, click the website address hyperlink to open the site
8. You should see three menus on the left pane:
Apps for SharePoint
Apps for Office
You have successfully created an App Catalog site.
The purpose of creating an App Catalog site is to enable you to upload applications from the local server using a few simple steps. To learn how to perform those steps, see Part Two: How to upload an application from the local server to SharePoint Online (O365).