opening an html file on an old iPad running IOS 9.3.6

An iPad 3 (early 2012) with IOS 9.3.6, the latest IOS it can run.

I hoping to find a way to load a web site and also find a way for the safari IOS app to open that site. I believe I need a file manager app, the choices are many (recommendation appreciated) and I have not found a way for safari to locate/open such a site (Does the file manager app need to be present for safari to have an "open" choice?). The file site to open is contained in a folder with 20 MB of data in sub folders and the starting point in the folder is a file named default.htm Simply opening this site is the only desired accomplishment on this well used iPad, the site is older than the iPad and no fancy capabilities needed. IF cannot be done I'll do something else; some of you experienced detectives have amazed me with your knowledge. Thank you.