What is the round metal object and the round donut piece with glue used for?
If this is your first camera, you many want to look at the FAQ. There is a lot more useful info there than what comes on the little sheet in the box. You will find that under the Support link at the top of the Wyze page.
The answer to your question is that it is a metal mounting plate. The camera has a magnet in the base so it will stick to anything a magnet will stick to.
From the FAQ
Can Wyze Cam be mounted on a wall?
Absolutely! Wyze Cam’s flexible design makes it versatile enough to place almost anywhere. Its magnetic base can be used on existing steel surfaces, or use the included adhesive tape to place the metal mounting plate on a wall.
If it’s more convenient to mount your Wyze Cam upside-down, you can flip the display of your Wyze Cam’s video feed. Enter the Camera Settings for your Wyze Cam and toggle Rotate Image 180° on/off.
You can toggle your Wyze Cam’s status light on or off. Enter the Camera Settings for your Wyze Cam and toggle Camera status light on/off.
The donut piece is a 3M adhesive used to glue the metal disk to a surface. You then attach the camera to the metal disk by the self-contained magnet in the base.
Use caution putting the 3M adhesive on any surface you don’t want to damage, especially a painted surface. The adhesive is very strong. Some folks have been successful attaching the disk with Commander Strips which are less damaging. But then there’s a risk of the camera falling.
When attaching to painted drywall, I have drilled a small hole in the permitter of the gray base (you can’t drill thru the center due to the magnet) and attached with a small wall anchor which is more secure and more easily repaired when removed.