What happens when you open this link: http://www.opera.com/download/get/?partner=www&product=android&utm_source=(direct)_opera_com&utm_medium=doc&utm_campaign=(direct)_via_opera_com ? It works fine for me.
Thanks, but I already posted a working link in my original message.
What bothers me is that the link on the official Opera for Android page is broken.
But can you explain how is the link broken? What happens when you try to use it, which URL exactly fails? It is likely that you can access the website, but the download link is blocked by the Great Firewall.
Regarding app stores, then as far as I know except of Google Play only Galaxy Store is actively maintained.