Or download the correct IPSW from the link below like I did last night and install via iTunes/Finder the links are direct to the IPSW files from Apple's servers, plus iTunes/Finder verifies the file so no worries of any issues.
https://www.redmondpie.com/download-ios-14-final-ipsw-links-ota-profile-file-along-with-ipados-14/
EDIT: Same links as provided below by Bouton Aide
https://www.redmondpie.com/download-ios-14-final-ipsw-links-ota-profile-file-along-with-ipados-14/
EDIT: Same links as provided below by Bouton Aide