Why is it not possible to log in to Netflix using the amazon fire stick?

I'm already registered with Netflix and Youtube and watch on my smartphone and PC. So that I can also receive Netflix and Youtube on TV (a bit older model), I have now obtained the Amazon Fire Stick. The registration of the stick and Amazon itself went smoothly. However, I can't download the Netflix app and other apps because the stick's menu doesn't let me continue (see first photo). I'm only given the "Buy" option. But it doesn't work either (see second photo). The option "download for free" can't be activated at all. Does anyone know what the problem is?

Amazon is competition from netflix, so of course they don't support it. You should have got n apple tv or n chromcast.

So it's fine with me.

Thanks for the answer, but I didn't want to pull the dongle from my cell phone or PC.

Apple tv runs without a mobile phone, but is also very expensive compared to the rest.