The ultimate goal of creation — to bestow the ultimate good on God's creatures.
The purpose of creation is to bestow the ultimate good on creatures — and the good must be earned.
Why is there a creation at all? Klach's answer is direct. The creation exists for the sake of its creatures, so that they may receive the ultimate good He wants to give. The chapter introduces a doctrine that runs through the rest of the book — the bread of shame — and forecasts the cycle of creation that makes the bestowal possible.
The most natural way to think about a generous gift is that the giver simply gives. But there is a kind of receiving that is unsatisfying — receiving something you have not earned. The recipient feels what Ramchal, following the Talmudic tradition, calls bread of shame: the bread is real and the food is good, but the act of receiving it for nothing diminishes the joy. A gift fully received is a gift the receiver has earned the right to receive, and there is no shame in the bread.
From this small observation comes the cosmic plan. If God's purpose is to bestow the ultimate good — not just any good, but the unending good of His own revealed oneness — then the recipients must be in a position to earn it. They must be free creatures with intelligence, with a moral stake, with the capacity to choose service over self-interest. They must be able to do something that makes them deserving. None of this is possible in a world without choice; none of it is possible in a world without difficulty. The cosmic apparatus that produces such creatures and gives them the conditions to earn the ultimate good is what we call creation.
This is the deepest reason the cycle of creation has the shape it does. The middle phase, with its difficulty and its evil and its long working-out, is not an unfortunate detour from the goal; it is the goal's operational form. A creation in which the recipients had nothing to do would be a creation in which the bestowal could not be complete, because there would be no earning and therefore the bread of shame would persist. The cycle is the architecture of earning, and the earning is the architecture of the gift.
Notice how this fits with what Op. 1 and Op. 2 have already said.
The bread-of-shame doctrine returns operationally at Op. 58 (the moon-mystery — Malchut as glass-that-does-not-shine, beautiful through the Sun, earning her radiance through service) and at Op. 125 (the parallel partnership of Zeir Anpin (Z"A) and Nukva — man's service elicits God's influence). And the cycle whose shape Op. 3 forecasts is named formally at Op. 16 (one cycle from Eyn Sof to Eyn Sof) and reaches its operational completion at Op. 138 (the eight-stage Coupling order through which actual deeds are integrated into the cosmic flow).