C++11 has fixed the ‘double closing angle brackets’ issue, but that is not the problem here. The problem is that properties with a non-default allocator (doesn’t matter which) are not supported right now.
The error message is not helpful; we will fix that. However, you will need to change your code to either not be a UProperty or not have a fixed allocator.
Sorry for the confusion that you may have been experiencing here. As Steve mentioned, non-default allocators are not supported with TArrays that are exposed to the Editor. I read through the post that you linked and did not see any mention of UPROPERTY being used, so I believe the intention was to provide examples of how to allocate memory for TArrays used in code, and not exposed to the Editor. However, I can see where this could be potentially confusing if you start with the assumption that the TArray is being exposed to the Editor as a UPROPERTY. I will check and see if we can do anything to make this a little more clear.