Once installed, you'll have access to the App Store via a blue App Store icon in your Dock or via your Menu Bar. Download sizes vary, but it the system update can be as large as 1GB. To use the Mac App Store, you'll need to upgrade to OS X 10.6.6 via Software Update which is available here.The one downside is that installing apps will try to force your Windows account into a Microsoft. Now, in Windows 10, it doesn’t totally suck. With Windows 8, Microsoft added its own app store.