@foe I just posted some similar answer to a different thread, but it comes down that I found a solution.
The reason that Deezer doesn't work is because Deezer probably sees that you are using Opera which is officially an unsupported browser and will then use the flash player as default.
But Opera has full support for HTML5 so the only thing you need to do is tricking Deezer in thinking that you're using an supported device.
I did this with this amazing plug-in: https://addons.opera.com/en/extensions/details/user-agent-switcher-5/#feedback-container
I configured the plug-in to use Chrome as this is an officially supported device, after this I went to Deezer and it worked.
So no need to install Flash, because now Deezer will just use the HTML5 player. Which is far more secure and way better then flash in my opinion.