To configure FileZilla to use a private key for SFTP access, follow these steps:

• Transfer the private key file to the client computer.
• Download FileZilla and install it on the client computer.
• Start FileZilla.
• On the Edit menu, click Settings. The Settings dialog appears.
• Under Select Page, click Connection, and then click SFTP. A list of currently installed private keys appears.
• Click Add keyfile.
• Browse to the location where you stored the private key file in step 1, and then click Open. FileZilla adds the private key.
• Under Select Page, click Interface.
• Under Behaviour, clear the Do not save passwords check box.
• Click OK.
• On the File menu, click Site Manager. The Site Manager dialog appears.
• Click New Site, type a name for the site, and then press ENTER.
• In the Host text box, type your site’s domain name.
• In the Port text box, type 22.
• In the Protocol list box, select SFTP – SSH File Transfer Protocol.
• In the Logon Type list box, select Normal.
• In the User text box, type your A2 Hosting account (cPanel) username.
• Leave the Password text box blank.
• Click Connect. After a few seconds, FileZilla establishes a connection to the server

That’s it. you are ready to go