(the): Use this if you are referring to the upload or the link from the site "Altadefinizione01." Since Altadefinizione starts with a vowel, it takes the elided article l' .
Example: "**L'**Altadefinizione01 1080p di Joker è disponibile." Joker 2019-Altadefinizione01 1080p-HD-iTA
The string you provided looks like a typical filename used on Italian streaming or torrent sites (like Altadefinizione ). In a casual sentence, most Italian speakers would simply say " Il film Joker..." or refer to the specific version as " Il file di Joker..." (the): Use this if you are referring to