Some instructions are given in hackaday project page
If the Arduino IDE doesn't have by default the board "ESP32 Dev Module", then go to Settings (Arduino IDE menu), then be sure that in Additional boards manager URLs there is:
https://espressif.github.io/arduino-esp32/package_esp32_index.json
Where name is starting by "Minitel1B", the following lib must be added:
https://github.com/iodeo/Minitel1B_Hard (forked from https://github.com/eserandour/Minitel1B_Hard)
Minitel1B_Websocket_Client and Minitel1B_Telnet_Pro require this additional lib:
https://github.com/Links2004/arduinoWebSockets
Minitel1B_SSH_Client and Minitel1B_Telnet_Pro require this additional lib:
https://github.com/ewpa/LibSSH-ESP32
Minitel1B_Telnet_Pro requires this additional lib:
https://github.com/bblanchon/ArduinoJson
keep version 2.0.x of esp32 library (don't jump on 3.x.x), like in this screenshot:
