I just tried the MAC-telnet client above from GitHub, compiled from source from release v0.6.3, and mactelnet fails to connect too. macping works like you experienced.
WinBox in on the same Linux installation in MAC WinBox mode has no problem connecting to the same router (CHR test installation). And I've reset that CHR installation so that there is absolutely no firewall rules.
It looks like the tool is no longer compatible with the recent RouterOS versions.
Do you have another RouterOS device on the same layer 2 network? If yes, you can connect to that device, then from that device's terminal, run
/tool mac-telnet host=XX:XX:XX:XX:XX:XX
to try to connect to the mAP lite. If it works, then the problem is definitely the opensource client.
Someone posted a new opensource implementation today, but it require .NET 10 (and the .NET SDK if you want to compile)
MacTelnet implementation for .NET 10 (KC.MacTelnet) - RouterOS / General - MikroTik community forum
I haven't tried that yet.