Plugin to register gym members and auto check for expired membership

2 weeks later after I finished my client website, Adding/Displaying Members functionality on Gym Builder Plugin broke down, just simply doesn't work. That happened after I got paid (4h ago).

I've tried every method, every way to fix this issue or finding a plugin replacement of Gym Builder, couldn't find anything. I even removed the custom codes that i made for my client on theme functions files, still nothing happened.

Please help me, I have no clue what to do. I'm not even good programmer with php i only know C, Py languages.