Poly meshes - Please help me

I would like to create poly meshes in unreal but none of the tutorials I have looked at worked. I want to create it to look like this:

This would be a solution:
For the meshes, you dont create them low-poly in unreal, you make them in a 3 application. look on the marketplace for “island” there you find a set of such assets.
for the landscape/water you need a special shader, search the community forums for such examples.!

Ive looked at this one but honestly none of it makes sense and I have no idea how to do it. Im fmailar with blueprints a little bit but im still learning in unreal. If you could add me on skype and help me that would be great. My skype is toshritzy.