Generating WeChat QR Codes

I' working on a login page where I want to use WeChat as login option and I have a WeChat official account. In my understanding of the documentation it's supposed that the next link would generate a QR code to scan and after the user authorization redirects somewhere else...:

https://open.weixin.qq.com/connect/qrconnect?appid=wx8bxxx21bxxxx0fxxx&redirect_uri=https://myhostname/oauth2.php&response_type=code&scope=snsapi_login&state=101#wechat_redirect

But the link doesn't work. I don't know if I'm missing something or maybe the site https://myhostname/oauth2.php has to have a previous authorization call to WeChat... ???

Somebody has worked with this WeChat stuff?

Thanks in advance!

I realized later that you must have a WeChat Open Platform Account, where you register your web application, wait for approval, and then give it the login permission to get access to that QR Code functionality