You can get the entire world file from ellacharmed's Wordpress site here: https://ellacharmed.wordpress.com/2013/10/05/isla-paradiso/ Click on the link to the Google drive location. That will save you the trouble of putting together a multi-part rar file.
As for installation: you need to put the world file in the same place an the original. Instructions are on MTS. As I recall, the instructions seem complex because they make sure you back up everything properly. It really comes down to finding the right folder and renaming files (changing the extension). Alternatively you could make a backup folder somewhere and use folder names to signify which IslaParadiso.world file is the original and which is ellacharmed's fixed version.
If you have any specific questions I could try to help, but I don't think I can explain it better than the instructions on MTS. Ok, I just went and checked, and
the instructions page has changed; it's much better than when I did this for other worlds.
You might also want to
check out this thread.
I have IP, but haven't gotten around to using any of those suggestions. I also have ellacharmed's fixed version, but I don't think I've installed it yet. I do use ellacharmed's fixed versions of other worlds.