Great. It is broken after Opera 66 update. Chrome version is 79 right now. I have no problem with Youtube videos but I cannot access Spotify.
I learned last version from this link: https://dl.google.com/widevine-cdm/versions.txt
Then downloaded last Widewine library using this link: https://dl.google.com/widevine-cdm/4.10.1582.2-linux-x64.zip
(This is what afore-mentioned script does)
All settings are correct but Opera doesn't play DRM content. I have updated this file too:
"preload" : "/opt/google/chrome/libwidevinecdm.so"
"preload" : "/opt/google/chrome-beta/libwidevinecdm.so"
"preload" : "/opt/google/chrome-unstable/libwidevinecdm.so"