import ftplib
host = "*"
ftp_user = "*"
ftp_password = "*"
filename = "picture.png"
con = ftplib.FTP(host, ftp_user, ftp_password)
lf = open(filename, "wb")
con.retrbinary("RETR " + filename, lf.write)
lf.close()

import os

with ftplib.FTP(host, *credentials) as ftp,
     open(os.path.join("директория", filename), "wb") as file:
    ftp.retrbinary("RETR " + filename, file.write)