I need help fixing my website.

My friend kindly created a website for my sports goods store. He sent me an archive, which I uploaded to GitHub, but it doesn't work. When my friend tried to run it, an error occurred that he couldn't figure out, so he handed the site over to me. He didn't go into details about the error, just mentioned that it appears right upon launch. I need the website in the next couple of days, as the store opening is scheduled for soon. Please help me.