Trying to direct page to a server folder and .htm file

Hi,

I am using some new software that requires I save a ton of files in a folder on the server. The issue is that I don’t know how to make a specific wordpress page point to that folder and specifically one of the .htm files. I do know that the ulr needs to be in this format:
http://www.mydomain.com/foldername/filename.htm

Here are some inconclusive thoughts I’ve tried to research thus far:
Add some kind of code into the HTML page tab to direct the url to that folder/file?
Create a call in .htaccess?
Create a call in index.php?
Or maybe all of these are off track….

Thanks in advance.