Download following components to get start with Sharepoint apps development.
Microsoft Exchange Web Services:
Click on the following link to download VS2012 project template to get start with the development of Sharepoint 2013 / O365 version.
Microsoft Identity Extensions
Workflow Manager Client 1.0
Microsoft Workflow Manger Tools
Working around with the error: An error occurred whilst trying to load some required components, Please ensure the following prerequisite components are installed.
Microsoft Web Developer Tools
Microsoft Exchange Web Services”
To get this error solved, Uninstall Microsoft Exchange Web Services from Control Panel, if its already installed. And navigate to the location of EwsManagedApi32.msi. In my case, its at: c:\Users\Zia\Download> In the command prompt, run
c:\Download> EwsManagedApi32.msi addlocal=”ExchangeWebServicesApi_Feature,ExchangeWebServicesApi_Gac”
It will initiate the installation wizard and I hope this will solve your problem.