Glass of milk, greek yogurt, fruit smoothie, multiple vitamin. Is this ok to live off of? Will I get amino acids?

Not balanced diet. It is not healthy to eat such a limited diet. You will get enough Amino Acids but this diet will lack essential omega 3 & 6 fatty acids & important micronutrients from vegetables. I advise adding nuts & seeds (esp. Almonds, walnuts, hemp seeds) and veggies of all colors (the different colors are made by different phytonutrients).
No. It is great food but not enough intake for a growing 18 yr old guy for24 hours. It lacks enough protein and amino acids.
Whose idea is this? If you have a family member or special person who is a food faddist / cult member, and they are trying to force you to do this, then tell them you're old enough to think for yourself. Your protein intake will be marginal, you may be sugar-loading, you'll become iron deficient unless you supplement more, and -- forgive me -- you're inviting ridicule. You're almost a grown man. Vary your diet.