Play DRM content on Chromium
You need the widevine plugin, which ships with Chrome and Firefox by default but isn’t available for Chromium.
Install the package chromium-widevine. If the problem persist, manually copy the files libwidevinecdm.so and libwidevinecdmadapter.so from a Chrome install (/opt/google/chrome/) to /usr/lib/chromium/.
Or
wget https://dl.google.com/widevine-cdm/1.4.8.1008-linux-x64.zip
unzip 1.4.8.1008-linux-x64.zip
sudo mkdir /usr/lib/chromium
sudo mv libwidevinecdm.so /usr/lib/chromium
sudo chmod 644 /usr/lib/chromium/libwidevinecdm.so