Hi, @piombinilorenzo1987

Thanks for coming back.

The first error message:

C:\Users\Lorenzo Piombini.ssh> ssh -i private root@droplet-ip
Warning: Identity file private not accessible: No such file or directory.
root@droplet-ip: Permission denied (publickey).

is quite self explanatory, the key was not find - No such file or directory.

If you try to ssh from linux machine there is an option to specify the key with the ssh command using the -i

-i identity_file
Selects a file from which the identity (private key) for public key authentication is read.  The default is ~/.ssh/id_dsa, ~/.ssh/id_ecdsa, ~/.ssh/id_ed25519 and ~/.ssh/id_rsa.  Identity files may also be specified on a per-host basis in the configuration file.  It is possible to have multiple -i options (and multiple identities specified in configuration files).  If no certificates have been explicitly specified by the CertificateFile directive, ssh will also try to load certificate information from the filename obtained by appending -cert.pub to identity filenames.

The second error refers that something might be wrong with the ssh-ley itself:

C:\Users\Lorenzo Piombini.ssh>ssh root@droplet-ip
root@droplet-ip: Permission denied (publickey).

You can also access the droplet using the console from your account and check if the ssh-key added on the droplet is correct. Another option is to create a new key and upload it to your droplet and try to access the droplet from the cmd again.

Hope that this helps!
Regards,
Alex