Usce on "500 internal server error when try to open wp-admin?"

Hi,

I am building a weshop/website, and everything was ok than randomly when I tried to login in wp-admin I got this error 500.

And it only appears when i try to open wp-admin, my site is oppening fine

http://www.jadranbiro.hr

And also I can open customizer, when I login i got error 500, but when I open site I can customize it, but as soon as I try to open admin panel, problem cames in?

I have some nulled plugins, can that be a problem?

And also random folder in my cpanel appeared MM_CASETEST4291?

Does someone have some solution?