Sugar us deprecated, and not updated to build for Elements later than v9.2.
Elements RTL (aka RTL2) is being regularly maintained and the current top revision will often require the very latest compiler, too. In this case, [Equals] was added in 2369, and you’ll need that version of the compiler (or later) to build latest RTL2.
(of course, as Carlo mentioned, each version of Elements also ships with a version of Elements RTL that will work out of the box).