The following Diagnostic log is displayed, however all tests during installation passed:

Attempting to load XAPI32.DLL Library into the Managed AppDomain for execution. Current Identity is '(domain)\IUSR_(servername)'

SUCCESS: LoadLibrary was Successful! XAPI32.DLL is now loaded into the Managed AppDomain and ready for execution.

FreeLibrary has been called on XAPI32.DLL!

Attempting to open an Sage 300 Xapi Session to the Company='VMI53B' using Username='ADMIN' and Password='*****'...

FAILURE

FAILURE: Failed to open an Xapi Session because: 'A Sage 300 XAPI USER ERROR has occurred with Extended Error Code 1. Please see your system administrator.

This indicates a security issue. We recommend that you create a new account for this site called VMEP. We can see from line 2 that VMEP is trying to access Sage 300 using the default IIS user. Make sure that the new account has correct Web User Rights. Assigning that user to the VMEP website is explained in Post Installation Tasks.