I don't think mining xmr through a web browser is efficient enough to make up even for the electricity costs. When mining through a pool the daily payout is very low (using an average cpu or gpu) - one can ofcourse do it as to support the network or simply for fun.

The very fact that they asked you to invite members is to get ads money through all the impressions, therefore obvious scam trying to make some google ads money. Don't waste your time trying to withdraw or get in touch with them.

Generally, all cloud mining and such are scam only.