Error occurred in deployment step 'Install app for SharePoint': We're sorry, we weren't able to complete the operation, please try again in a few minutes. If you see this message repeatedly, contact your administrator.
Your account used to log in as user who developing the SharePoint app does not have necessary acess permission on the "App Management" service database.
If you are working on your local VM or DEV server, you are welcome to log in to SQL Server and add the user as shown in this figure.
And give the db_owner and db_securityadmin on the schema owned by the user and also select the db_owner ,db_securityadmin and SPDataAccess on the database role membership.