HDCP error

I’ll assume you’re trying to play the movie entirely on the Mac, and not using any external display.

Any add-on cleaners, add-on anti-malware, add-on anti-virus, add-on VPN clients, or add-on firewalls installed here?

Does the movie play when booted in Safe Mode?

As a test, disable screen sharing, and try again.

Turn Mac screen sharing on or off - Apple Support

How can we know the hardware and software configuration? Please download and enable full device access for and post the output of EtreCheck. Open a new reply here, and then press the button that looks like a printed page to get a text input box big enough to paste the entire hardware and software configuration report here.

Your immediate course of action ought to be to contact Apple to report a problem with your movie purchase, since it's unreasonable for them to expect you to pay for a service you can't use:

https://reportaproblem.apple.com

Greetings changbaoling,

Thanks for visiting the Apple Support Communities! I understand you're unable to watch a movie you've purchased from the iTunes Store on your Mac, as you're receiving an HDCP error upon attempting to play the content.

I suggest restarting your Mac, attempting to download the video, and reporting the issue if the behavior persists. You can see those suggestions from the following article: If you can't stream or watch movies or TV shows from the Apple TV app, iTunes Store, or third-party apps - Apple Support

Kind regards.

Please enable full drive access in EtreCheck, and post another report.