Where can I find the User manual for Hogarlabs PD11C Dehumidifier?

You can see the video of the dehumidifier at the link shared below:

Why do auto drain dehumidifiers have hose connections at top of water bucket instead of the bottom? I will always have a full bucket of water

When you connect the water pipe for continuous drainage, the water will be drained from the water pipe first, so the water will not flow to the bucket. It designs the continuous drainage outlet on the top of the tank to better assist the continuous drainage pipe for gravity drainage.