It's not just Chinese labs that do this, lots of companies upload a README to a GitHub repository then link that repository from the website, I guess so they can have a GitHub icon somewhere on the website?
Submission is basically a form for requesting access to their closed API (which ironically is called "OpenPlatform" for some reason).
> which ironically is called "OpenPlatform" for some reason
This is pretty weird, the original text is 开放平台, but it basically is another name for "API" in China.
Not sure who started this, but it's really popular, for example, WeChat has an "Open Platform": https://open.weixin.qq.com/. AliPay too: https://open.alipay.com/. And peak strangeness, Alibaba Cloud (whose API is largely an AWS clone): https://open.aliyun.com/