PC HOW TO CHANGE THE ALPHA VERSION OF MY SERVER RAT3 OR RAT4?

[RASPALOCO]

I have been trying for hours to change the version of my server because when I create it, it is always created in version Alpha 21.2 (b14).

I try to set it to version Alpha 21.1 (b16) but nothing I do works.

Could someone tell me how to proceed, I have tried with both Rat3 and Rat4.