To unlock this achievement, you will need to open every CLEO drop that appears on the field between waves, and then survive Wave 7 to victory. By "you," that means
you, not you
or a teammate. By "open," that means approach the drop and press
to open it. You
don't need to empty it out or remove any items from it "just to make sure." Any other solution, or comment to another solution, saying you need to remove an item from each one, remove a stack, empty it, or whatever, is
wrong. I unlocked the achievement after simply opening and peeking at many of the drops.
You can do this in a solo game, but it may be difficult, because between repairing walls, healing the tech, placing mines, etc., you may have insufficient time to open each drop and still put yourself in a favorable position to win. But, it can be done.
It can also be done in a multiplayer match, but the challenge there is that if another player empties a CLEO drop, it self-destructs so that you can't open it. So, if you're having trouble, the easiest way is to get in a match with one other human player and have him/her agree not to empty any of the drops. Even better, have that person agree to let you open all of them first while he does wall repairs, then he can go behind you and take your leftovers from the CLEO drops. When a drop has been opened by any player, it changes color and stops pulsing on the minimap, so where there are many drops on the field, if you know you're the only player opening them, you can tell at a glance whether you've opened it .
EDIT: BRANIAC1972 writes, "I can confirm as of 27th of July 2019 only the host gets the achievement if they open all 25 Cleo drops." Tnxk then adds, "As of May 10th, 2020, you do not have to be host to obtain this achievement. You just have to be the first to open up each supply drop!"
The number of drops after each wave is:
Wave 1 - 0
Wave 2 - 4
Wave 3 - 4
Wave 4 - 5
Wave 5 - 6
Wave 6 - 6
Total: 25