If your legal documents have expired or are no longer up-to-date (based on changes to your current legal or business status), you won't be able to get paid for the work that you do on Malt.
But there's no need to panic. All you need to do is re-upload the expired documents by clicking on "Business Settings" in the drop-down menu that appears when you scroll over "My Freelancer Dashboard" in the upper right corner of Malt (when you're signed in).
The documents you're asked to provide may vary based on the country where you reside, but the usual suspects typically include your ID or passport, business registration number, articles of incorporation, etc.