The included script 'widevine-flash_armhf_64.sh' fetches a ChromeOS image for ARM and extracts the Widevine and Flash binaries, saving them in a compressed archive. Since it downloads a fairly large file (2Gb+ on disk after download) it is recommended that you run the script on a raspberry that has plenty of disk space.
The files in the compressed archive are copied to the folder /usr/lib/chromium-browser/
To run the file just type the following:
sudo ./widevine-flash_armhf_64.sh
Check out this tutorial: https://lemariva.com/blog/2020/06/raspberry-pi-amazon-prime-netflix-and-drm-solution