I just checked their telegram and it was mentioned that withdrawal of tokens earned with staking is every 15 days. Only profit can be be withdrawn every 15 days...not the actual investment which will be locked for 6 months.
I'm just getting to know about this and must confess that it's a welcome development. The fact that investors have the option of withdrawing their interest could give them a reason to invest more, so as to have passive income. I guess there's a minimum amount that could be withdrawn to avoid the issue of very low withdrawal and congestion.