How to connect via FTP to the ubuntu server if the connection is made using an RSA key?

Question

Computer networks

There is a server on ubuntu 16.04 on DigitalOcean. I connect via ssh using the following command:
ssh -i configs/algo.pem [email protected]
RSA PRIVATE KEY is in the algo.pem file.
How to connect to the server via FTP in this case (that is, I kind of don’t know the login / password, there is only an RSA key)? Is it possible to connect via FTP to transfer files in the console? And how to connect via an FTP client, for example, Transmit or Commander One?

Answer 1

log in via ssh, create a regular user, specify a password for him.
just don't go to ftp as root....

Answer 2

You can connect via SFTP. Judging by the answers of the search engine, both clients support SFTP, which means that somewhere in the settings it is possible to specify a private key.

Answer 3

Ruslan Fedoseev , are both SCP and FTP protocols intended for file exchange? Does one have significant advantages or are they for different purposes?
And if I don’t remember (I don’t know, I never set) the password for the root user, then should I change it using the passwd command?
I also have "PasswordAuthentication yes" in "/etc/ssh/sshd_config" - does this apply to all users or does it allow only the root user to log in with a password?