You have installed Vault Server 201x on a 64 bit OS and let it automatically install SQL 2008 Express SP2 (32 bit) on a 64 bit machine.
Your end-state goal is
64 bit OS
AUTODESKVAULT running in a 64 bit SQL 2008 Standard\Express\Enterprise (R2 or not R2) SQL instance.
Microsoft does not support cross platform upgrades from 32 to 64 bit. (See "Version and Edition Upgrades”This means that if you then manually install 64 bit SQL, it will not upgrade the exisiting 32 bit AUTODESKVAULT instance to a 64 bit instance.
You will need to
1) Uninstall SQL Server 2008 (32 bit). (No need to uninstall Vault Server as well)
2) Manually install SQL Server 2008 (64 bit) (Standard, Express (R2 or not R2) as per the Advanced Configuration Guide.
3) Create and configure the VaultSys account as per the Advanced Configuration Guide
4) Create and configure the ADMS-<Computername> account.
Open the Microsoft SQL Server Management Studio.
Expand the Security -> Logins folder.
Right-click on the Logins folder and select New Login.
Type ADMS-* for the login name.(Where * indicates the NT Computer name) Example, if the computer name is MAINSERVER then the login name would = ADMS-MAINSERVER
Select SQL Server Authentication.
Enter the correct password. The correct password can be found web.config file here "C:\Program Files\Autodesk\ADMS Professional 2013\Server\Web\Services" on the "<siteSecurity generateUser" line.
Note: I am not allowed to publish passwords on this blog for security reasons, although I am allowed to write where to find them.