I was confused why I can’t use the apps which were downloaded from my PC to SD Card in WebStation at my first trial. Then, I figure it out by myself that
1) it’s ok if you download apk directly via WebStation
2) if you want to move the apps from PC to WebStation(of course, in the SD card), you have to install an APK installer first and allow Third Party Application. After this setting, you can easily arrange your apps!
Share with you guys.