This information may be different for different versions of the Mac OS.
In the Console found in the LaunchPad go to Other -> Console. Then look for the ~/Library/Logs/com.sourcegear.vault.guiclient.log file.
If logging needs to be enabled this can be done by editing the Vault 'package' (right click the Vault application and select Show Packages). Inside the Vault-package/Contents/Resources/configuration/com.sourcegear.vault.guiclient/com.sourcegear.vault.guiclient.config, set enableLogging to "true" and classesToLog to "all".
CPC Log File on a Mac
Moderator: SourceGear
CPC Log File on a Mac
Beth Kieler
SourceGear Technical Support
SourceGear Technical Support