You should have a pair of active shutter 3D glasses as below.
Make sure that the keystone mode is on the auto mode.
Make sure the internet connection perfect, It is better if the optical network or 5G network.
If you do not like watching films online, you can save the films in a USB flash disk, insert the USB flash disk onto the port, open the film by using the projector directly.
Visit the website by Google Chrome, and find out 3D film sources. Open it by using the projector.3rd,
Press this button on the remote controller.
Turn on the power of 3D glasses, Wear the 3D glasses on.
You can watch a 3D film now.