Use SSH to fix your permissions using chmod and chown.

@carlosrpj

Unless you've installed and configured FTP software on your Droplet, you won't be able to use FTP and would need to use SFTP.

That said, generally this isn't required if proper permissions are setup to allow WordPress to read + write. How you'd go about this depends on whether you're using Apache or NGINX.

On Apache, www-data is the default user that needs to own your files and directories, so if you are running Apache, you'd need to set ownership on the files.

For example, if you're home directory (where index.php is) is:

/var/www/html

You may need to run:

chown -R www-data:www-data /var/www/html

NGINX works slightly different in that permissions need to be set for the user that is running the PHP process(es). By default, that's www-data as well, so the same command could be used.