How to enable root login on fedora?

I’ve followed this guide in order to install an instance of forem on digital ocean.
Well, I’ve succeeded 🙂 But the guide is using a key for login and I’m not able from the core user to access all the files of the script on the server I need the root login in order to access them through FTP.

I’ve already tried editing the sshd_config file and setting PermitRootlogin to yes and Strict mode to no, but I get this error:

Permission denied (publickey,password).

Any idea how to fix this?
Thank you in advance.