Welcome on board!
There are many, many more books available for download legally than just WOWIO.
The very first thing you should do is to click on the E-books link on the top of this page. Those are the highest quality free e-books you can get on the net. Each one is very well formated, proofread, and most probably available directly for your device.
Also see this page
https://wiki.mobileread.com/wiki/E-book_stores
with links to many Free and commercial e-book sites.
You might also want to search this forum for "Free ebook" and "Free e-book" and ... . Also have a look at the "Tor offer"
If you still insist on using WOWIO, try looking for a proxy server inside the USA. Then set your browser to use proxy server somewhere in options and try again.