I'm unable to restore a backup locally

Hello! The documentation I followed is here. I am using the latest PosgreSQL version 11 with PgAdmin 4. I would like to try again with PosgreSQL 9.6.5 as the documentation notes, if someone can share a reliable download link! I don’t know if using 9.6.5 would solve my problem as I’m having trouble restoring a backup as my .backup file is more than 50 mb and PgAdmin has the file size limited at 50 mb.   Please help!!