You are absolutely providing zero necessary information with that listing above.
If it results in a 404 Error, it means your path does not exist, so please check your html form of your registration page to where it leads in your backend.
Since i did not change anything after the installation the problem seems to be in the code itself. Otherwise maybe in the user permission...i dont know.
I will try to check the code for the registration. The provided landscape of code is not in the list of my known programming languages. Thats why i hoped for help or advice here