The included script 'widevine-flash_armhf.sh' fetches a ChromeOS image for ARM and extracts the Widevine binary, saving it 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 machine that has plenty of disk space.
To install the resultant archive, issue the following on your ARM machine–after copying over the archive if needed:
sudo tar Cfx / widevine-flash-20200124_armhf.tgz
(Where 'widevine-flash-20200124_armhf.tgz' is updated to reflect the actual name of the created archive)