这是网站引用的内容 –

The web Store also now has support for installing apps via SD card,
which many Windows Phone 8 models support. This option can be useful
when a cellular or Wi-Fi data connection isn’t available. Just look
for the “Download and install manually” link on the app’s details
page. Click to download the app’s installation—or.xap—file,which can
then be copied over to the phone’s SD card and installed. (See How do
I install apps from an SD card? for step-by-step instructions.)

要从SD卡安装任何xap,请阅读此博客文章 – http://www.windowsphone.com/en-US/How-to/wp8/apps/how-do-i-install-apps-from-an-sd-card