Vertus Fluid Mask

Vertus, the developer of fluid mask has shut down operations, so fluid mask is no longer available.

There are dozens of good masking applications, search and test for the one you are happy with.

Photoshop CC can't be beaten for intricate masking.

Only the developer would know.

Gerrybeane wrote:

Will Fluid Mask be updated to work with 64 bit Mac OS?

You will have to ask the developers of that product.