You need to use this method.
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part01.exe
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part02.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part03.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part04.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part05.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part06.rar
http://trial.autodesk.com/SWDLDDLM/2013/BDSADV/ESD/Autodesk_Building_Design_Suite_Ultimate_2013_English_Win_32-64bit.part07.rar
