Easy IoT is a simplest IoT Solution presented by DFRobot
To integrate the Firebeetle ESP32 into the Arduino IDE you need to add an additonal Board to the Board manager. Therefore go in File->Preferences, find Additional Boards Manager URLs.

Now the Wiki says I should add
https://git.oschina.net/dfrobot/FireBee ... index.json
But the server behind this URL is damn slow so that I (from Europe) not able to load/integrate the Firebeetle board in my Arduino IDE.

Any ideas to solve that?
I have the same problem - just received the Firebeetle_ESP32 from DFRobot and followed the instructions to add the board to the IDE Boardmanager.

What I receive is: Error downloading https://gitee.com/dfrobot/FireBeetle-ES ... index.json

I tried:
https://git.oschina.net/dfrobot/FireBee ... index.json
https://gitee.com/dfrobot/FireBeetle-ES ... index.json

Always the same problem
And the GitHub link you posted does not show a Json file.