"Download 4K movies in Hindi." When using the plural "movies," you do not need an article. Indian — Sexe Girls Photos Verified
It is standard convention to write "4K" with a lowercase "k" (representing kilo/thousand), rather than "4k." Nonton Film Salahuddin Al Ayyubi Sub Indo [VERIFIED]
"Download a 4K movie in Hindi." You use the indefinite article "a" because "movie" is a singular countable noun, and you aren't referring to a specific one already mentioned.