It is 32bit also, the 32bit AmpliTube 3.dll is 197k, the 64bit AmpliTube 3.dll is 213k.
Did it ask for the VST folder.
http://www.ikmultimedia.com/products/amplitube/index.php?pp=amplitube-3-specs Windows® (32 and 64 bit)
Minimal: Intel® Pentium 4® 2.4 GHz or Intel® Core™ Duo or AMD Athlon™ 64,
1 GB of RAM, Windows® XP, Windows® Vista, Windows® 7, or Windows® 8.
Supported Plug-in formats: VST, RTAS, AAX (32 and 64-bit).
jBridge Using inter-process communication mechanisms, it aims to make it possible to run 32bit plugins in 64bit hosts, 64bit plugins in 32bit hosts, or even bridging 32bit plugins to 32bit hosts, allowing to overcome the memory limitations of a single 32bit process, in this last case.