So far the "social credit" on seems to be mostly based on how much you buy and it only seems to give you discounts to massively overpriced products (similar to a credit card reward system).
You don't really download apps in Wechat but rather add a link more like a Facebook App (JavaScript & HTML).
Chinese people tend to like one app that does everything. Most of the services talked about in the article as separate services that you can open in WeChat but you can also open most of them in AliPay or Taobao or access them directly on their own websites. This is what Facebook tried to do but failed...
What I find fascinating is that a lot of older people that use WeChat in China are illiterate apart from numbers. They do everything by remembering the pictures and other people help them to set up their account. That is part of the reason why they want a single app that does everything. You don't need to read since you can just send messages, look at pictures and iconography.
Also, everyone in China still accepts cash but you generally need correct change.
If you have any questions feel free to ask. I just found out my sesame-credit score is 622 (not that it does anything...)