Problems using Spotify Web version because DRM (Firefox & Chromium)

[Ekkaia]

Hello.

I'm trying to use Spotify Web version, http://play.spotify.com.
I tried on Chromium and Firefox, but both cases I'd been redirected to a Spotify message saying (for me in spanish, try to write on english): "The play of DRM content is not enabled" and a link to a how-to for both navigators:
https://support.spotify.com/es/using_spo...eb-player/

I have the configuration in Chromium that says the article, but still getting the same message.
In Firefox there are no option like said in the article.

Anyone knows how to use Spotify Web? (cause no ARM .deb version from the application)

Thanks.