Integrate a class with my buttons

Hi,

I can’t find the good code to integrate a class with my buttons on my wp admin Page (see the screenshot attached 1, 2,3)
https://floradoueu.cluster020.hosting.ovh.net/reconnexion/

I set this option :
Click – the pop-up will appear after clicking a defined element on the page.

Maybe you know how to fix this ?

Thanks in advance,

Catherine