I had exactly the same issue as everyone else here. Security assist put the .php files into the incorrect folder. A manual installation of the files into the correct folder was required.
Why is the fact that this happens not in the "Known Issues" for this extension? Why are the .php filea not included as a download for this extension?
Once again, multiple people are having this issues (as seen here on the forums) yet there is no mention of it in the "Known Issues" section of the website for this extension... so the users are left to search and figure out what was wrong themselves...!