For the latest system requirements and information, please visit Swank's Frequently Asked Questions.
Note: Swank playback in Safari is no longer supported on Macs running OS X Sierra and later. Please try Chrome or Firefox.
In Chrome, no plug-in installation should be necessary; Widevine CDM is now a component of Chrome.
From Mozilla Support:
"Firefox downloads and enables the Google Widevine and Adobe Primetime CDMs by default to give users a smooth experience on sites that require DRM."