Catch that catch may.

Whoever is able to seize an available chance or prize will do so; no one can count on having it reserved for them.

The saying presents the situation as a scramble in which people act for themselves, rather than wait for an orderly division.

Use it when several people have a chance to claim something limited, such as an opportunity or a share of goods, and those who act successfully will get it. It describes the competition without necessarily approving of it.