This article explains how to create an app catalog site in SharePoint 2013 using SharePoint 2013 Central Administration/PowerShell
. An app catalog site contains a special type of Document Library that is used to upload and store app package files. There cannot be more than one App Catalog site collection in a web application or each web application can have only one App Catalog site collection. There can be multiple App Catalogs in a farm.
1. Open SharePoint 2013 central administration.
2. Then choose Apps from the left hand side and this will open the Apps page. There click on Manage App Catalog from the App Management section in the Apps page.
3. Then in the Manage App Catalog page click on create a new app catalog site and then click on OK. Before that you can also check the Web Application or if you want you can change the web application.
4. Then this will open the Create App Catalog page, there you can enter the Title, Description, URL and Site Collection Administrator and then click on "Create".
Create App Catalog Using Windows Power Shell
New-SPSite -Url http://sp:1001/sites/AppCatalog -OwnerAlias "serverName\sp_admin" -Name “App Catalog site" -Template "APPCATALOG#0"
The SharePoint 2013 app catalog site would be successfully created using central administration/PowerShell by following this article.