I think they pay only once you reach minimum threeshold
there are options for something like 5800 Satoshi and 1 Million satoshi
Yes but the wallet has been passing by some troubles and even users with the minimum threshold are not being paid.
Seems it is Op's situation, by what I see in the topic
The biggest problem with mircowallet is that they have very poor communication with its users. The owner haven't logged in his bitcointalk account for over a month, and made no update on the site or on bitcointalk.