files are being downloaded with .html suffix Every time I download a file from my school site, it gets .html suffix.
For example, if I download a file called file.docx from my school site through the safari, it is saved in my downloads directory as file.docx.html.

This issue happens just at my school website and not at any other website whatsoever. Additionally it happens just through Safari and not through Chrome or any other browser.

How can I resolve this?
This is outside of your control - the headers being sent by the school's web server determine what file type Safari thinks it is, and therefore appends the extension it thinks is appropriate. In this case, most likely the Content-Type and/or Content-Disposition headers are not being sent, or not being sent correctly. See this for a more technical explanation.