To encrypt an archive in 7-zip, once you’re at the Add to Archive dialog box, enter a password and select the Encryption method AES-256.

Learn how to add a Password to zip files. Using free 7-Zip, you can encrypt & easily add a Password to zipped, archived & compressed files.

With the file open in Pages, Numbers, or Keynote, select File and then Set Password to choose and apply your password.