Please help web server question

[Oksey]

Hi,

I made one small Html web thinking that is going to be hosted on Windows web server. I tested the web on the internet and works fine under Windows.
That agency I made a web for delivered it to the client and this client passed it to their web server provider.

Now my problem is: The Web Server provider is running a
Linux server and is saying that the web is not possible to run correctly on Linux, he didn't want to give any more details, what needs to be changed to make the web run well.

I need to know more about Linux, what I have to be careful about, what can be used and what not.
The web is pure .html using .css, libraries and templates,

Can anyone please help. I rally need urgent Help

Thanks,

Oksey