Hey there, whenever I try to install the FSX St. Barths, I get this error:

Google translate says:
St Barth FSX has not been fully installed for the following reason:
Can not create file:
blablabla (filename)...
You must restart the program once again to install St Barth FSX
I am trying this:
Fs_marcoh
I even tried redownloading it but that didn't work. Is there another freeware scenery that is like this or better, or is there a way to fix this?
(by the way the folder isn't hidden and it's not read-only)