When you download encrypted files from the same PC using the same DriveHQ FileManager or DriveHQ Online Backup program that uploaded the files, you don't need to enter the encryption key as the key is already cached.
However, if you try to download files using Internet Explorer or third party FTP client software, the downloaded files will still be encrypted.
If you download files from another PC using FileManager or Online Backup, then the first time it will ask for the encryption key. After that, the key is cached so it won't ask again.
DriveHQ encrypted folder is more secure than HTTPS or secure FTP as files are encrypted locally and stay encrypted on DriveHQ.com. Which means your files cannot be viewed by DriveHQ support staff and any potential hackers. However, you need to make sure your files are safe on your own computer.