Do you mean the wireless password? You could find it on the bottom label on the router.

For now, 8200ND only have v1 , can you confirm whether it's v1 or v2? http://www.tp-link.com/en/download/TL-WN8200ND_V1.html#Driver

1. T2UH support Win10 now. 2. Yes. 3. It could use 2.4G and 5G , and it's easy. But you also need a wireless router which support 5G.

1. 725N doesn't support 5G Wireless. 2. No , 725N v1 can not install the driver of v1.

You could try to install the adapter on another USB port or another PC . If this problem also happens on other PC, I suggest you could try to contact with your retailer to replace your product.

You could try to press the wifi button for 5s to enable the Wi-Fi . Or login the management page of the 4530 to enable Wi-Fi