You can get any kind of molecules in the lab you like with enough technology. If certain elements can bond together in nature, it can be reproduced in a lab someway or other so such an experiment does not prove anything. What would prove it is if the experiment was conducted under conditions which were similar to those that occur in nature. The conditions under which the Miller-Urey experiment was conducted have been shown not to be those which occurred in nature.
In addition to which, it was the wrong way to do things. Nature produces amino acids through DNA being transcribed by RNA into amino acids and then stringing those amino acids together to produce proteins. You can have all the amino acids you want, all the proteing you want and you will never get DNA.
In short, Miller-Urey was utter nonsense when it was made, it is utter nonsense now, and evolutionists and materialists are perpetrating a humongous lie by continuing to use such nonsense as proof of their beliefs.
These experiments were very, very low tech. The Miller/Urey was the first of these. Subsequent experiments demonstrated that nucleotide bases can also arise spontaneously in mixtures contaijing HCN. Besides the nature of the original self-replicator may not necessarily have been nucleic acid based.