Hello
the relevant error seems to be:
fatal: no matching mac found: client hmac-sha1,hmac-sha1-96,hmac-md5 server hmac-sha2-256,hmac-sha2-512 [preauth]
Converter uses OpenSSH 5.7 which, it seems, doesn't implement sha2 MAC. You could relax a little the source machine sshd (see man page for sshd_config) and try again.
I'll log a bug to upgrade Converter's OpenSSH in a future release.
HTH
Plamen