Problem with some ecommerce system (ERROR 500)

Hello, i bought some ecommerce system named UVODO. Everything is fine but when i want to make a checkout or register in frontend it makes me HTTP ERROR 500. Sometimes (or when i delete cookies in my browser) I can come in to checkout without this error but then its some another problem with infinity loading (i attach you a console error). UVODO is installed by me on VPS server and everything in admin panel for example is working fine but a problem is on frontend.. I cant do orders or new clients because of this error 500.. Please help me.