I've moved on from this Cayman Islands thing. Not gonna bother, FS4 is just around the corner next week so no need to deal with it.
Understandable if you have moved on.
As our private message shows, you might actually have an odd bug on your end, or the installation is still incorrect.
I will post the install instructions since it might be beneficial for others.
There are two official ways this install structure will work.
Last thing to verify and check would be to make sure you see these folders after 'cayman_islands_v1'
1. Documents\Aerofly FS 2\addons\scenery\cayman_islands_v1

Edit: Original download does not have 'elevation' folder. I added this for testing purposes.
2. SteamLibrary\steamapps\common\Aerofly FS 2 Flight Simulator\addons\scenery\cayman_islands_v1

Edit: Original download does not have 'elevation' folder. I added this for testing purposes.
If these paths do not work, then something else is wrong or not working.
Logically you could take all of these folders within 'cayman_islands_v1' and place them within
3. Documents\Aerofly FS 2\scenery

However, you would have to create parent folders and rename them with proper naming convention.
This can be done but requires proper understanding Aerofly FS 2 folder structuring.