Does anyone here use Vanpeople/Vansky?

I'm interested in purchasing an office chair off of Vanpeople (basically Chinese craigslist) but I don't speak Chinese.

Does anyone know how the app works? Can I just send a text message to the seller? Should I use WeChat?

Also do most people just take cash? I see that there's the ability to add a credit card to the app but ideally I'd like to just pay in cash.

Appreciate any help.