For signing in FTP you require 3 things:
FTP server, username, and password.
FTP server is ftp.domainname.com or ftp.hosting server IP e.g (184.108.40.206)
You can use your cPanel username and password.
On the off chance that you need to allow (restricted or full) FTP access to somebody, please sign in to your cPanel and make FTP accounts.