As a potential workaround to the problem you describe we recommend that you try the following:
Start the installation with a local admin on the VC machine, using the parameter as below.
VMware-vsamanager-en-5.1.0-825249.exe /v"VM_SHOWNOAUTH=1"
During the installation wizard, you will be prompted to enter username and password credentials.
Authenticate against VC using any account that has administrative permissions against VC,
this can be a SSO local account (for example vsaadmin@system-domain) or even a ldap account.
Thanks,
Ike