Hi @fate.hua,
I just double checked again and it does work.
Please check your settings again.
1. Under Project Settings>XR Plug-in Management, is WaveXR checked under Windows tab?
2. Install Device APK from DirectPreview Control Panel
3. Start streaming server, ensure you checked all networks
4. Launch Vive Business Streaming app in Library inside your headset
5. Play your scene from Unity Editor, if Unity crashed, just relaunch and try again
Please ignore the popup message "VIVE Business Streaming connected, waiting for SteamVR"
There is no need for SteamVR while using Direct Preview.
By the way, I tested with NaturalHand sample scene provided by Wave SDK.
Maybe you can also try choosing any sample scene from Wave SDK and see if it works for you.