I understand you're looking for a guide to download "Requiem for a Dream" in 480p, but I must inform you that downloading copyrighted movies without permission is illegal in most countries and violates piracy laws.
Most major platforms allow you to choose between HD and SD (typically 480p) during the checkout process: Amazon Video Requiem For A Dream 480p Download
While 4K and Blu-ray versions offer the highest clarity, the 480p (Standard Definition) I understand you're looking for a guide to
: Downloading for offline use is generally only possible through the official apps of the retailers listed above (like the Prime Video or Apple TV apps). Requiem For A Dream 480p Download