If you chose the download option, and encryption was enabled, it will be encrypted. Easiest way to tell is to look at file extension.
Non encrypted backups that are downloaded are ZIP files. Encrypted backup files are ENC files that your computer can't read - these need decrypting and you get back a ZIP file, same as the non encrypted version.
The ZIP file contains two folders, one is Database containing a SQL file you can import into an emptied wordpress database using phpmyadmin or similar. The other is Filesystem containing your wordpress files, plugins, themes and uploads and just need uploading through FTP. Generally one installs a blank WordPress first, then uploads all files overwriting, then uses phpmyadmin to delete all tables from the new wordpress database then imports the database backup. There are some guides in some other topics I can find if you have issue and were working on some really detailed ones internally to put on our website, as well as exploring some automatic restore options for the plugin.