I bought this App in the normal way but just could not get it to open any HTML files so I emailed support and they quickly replied with solution. Here is a copy in case it is useful for others.
Ok follow these steps,
Step 1, Tap the File button
Step 2, Tap the Open button
Step 3, Tap the file you wish to open
Step 4, Tap the button at the bottom right
Thanks, that worked 1st time. I thought the button on the bottom right looked like it was for creating a new folder.
I can now get going. App looks good but yet to use it properly. Cost £2.99