My page keeps re-directing to "Index of /sa" the a link to Parent Directory

I am now the webmaster for my work webpage. There was a webpage created: http://www.thsu.edu/sa. The page contains the following code:

<a href="http://www.thsu.edu/sa-classroom" target="_blank">THSU San Antonio Branch Campus</a>

That’s it. I have verified on html sandbox that the code should show a link to my school’s San Antonio campus.

But, when you type in the address: http://www.thsu.edu/sa it defaults to http://www.thsu.edu/sa/ and all that comes up is:

Index of /sa

Parent Directory

I don’t know what to do with that page. I have tried even just putting in generic code and it still goes back to that and it does not even give me the option to “Edit Page” when I”m in wp-admin like the rest of my pages does.