If you would like to download your website files to your local as backup, you can compress them first for easier downloading.
1. Login to your hosting control panel --> Files
2. Select the files/folders which you would like to compress, then click 'zip' icon
3. It will ask you the filename which you would like name it, write the name down and click 'Submit'
4. It will popup a box and tells you it is zipped, just click 'yes', you will find the zip file created there.
5. Now you can login to your FTP account to download the zip file to your local, after that, please delete the zip file from you account to release the space for your website and make your site running smoothly.