Where can you download action replay max duo software v1.07n?

Version 1.07 doesn't official exist. The highest that Datel/Codejunkies ever updated the Max Duo up to was version 1.06 for the general public.

A prototype v1.07 was released to special users who purchased the Max Duo shortly before they stopped carrying it, and doesn't work with Pokemon games.

You can download the software and the driver update (which took me a long time to dig up) right here at the official website:

Final v1.06 http://us.codejunkies.com/support/article.aspx?article_id=247

Prototype v1.07 http://host-a.net/coolbho3000/eu_update_v1_07.bin