So up front, the good, you can withdraw anytime, the bad, it's a 20% withdraw fee. That simply means, in 10 days you are in the green. You also need metamask or the trust wallet.
https//SmartEtherMiner.io/?ref=0x1880a1b5b5ab9df837db670f89f57940cbdc451e
Ladies & Gentleman, The Smart Ether Miner
Great Platform