Changing the agent header in your browser is probably enough

As I'm feeling spiteful, I want to add that you can easily block the ads with firefox + ublock origin on Windows. So it's hard to believe it's some technical thing related to securing the ad playback.

I haven't tried spoofing the user agent yet.

But even if it did the trick, I just don't get the reason behind blocking other OSes.

Now that I think of it, they probably just spout out the user agent my browser sent in the error message.

I would be fine with watching some ad supported movies if they let me...

Given that the first thing that pops up when I visit that site on my phone is "Allow DRM videos?", I'd venture to say that they don't "support" it is due to something like Widevine DRM content. You may need to look into DRM codecs and such on your OS.

And to add, like many sites, on mobile they try to make you install their app. Would like to just use the browser please...

User-Agent Switcher and Manager should do the trick.