Should I be able to log in to edit a website via any FTP client, or is my login info wrong?

One of the webmasters of an organization I have worked with uses Dreamweaver to edit their website. I have locally tested some HTML edits for said site's index page; the executive director of the organization gave me the site's login credentials (IP address; username; password). I have tried signing in via FTP (FileZilla, at least), but have not been successful doing so.

My question is: Should I be able to log in to the website via any FTP client (even though the webmaster uses Dreamweaver)? Or, if I can't log in via standard FTP clients, does this suggest that the login info I have been given is incorrect? Are there any other possibilities I may be missing?

The site is hosted via an AWS virtual server. I also have the login creds for this Amazon account, though I don't think that's relevant here.