Historically, when Universe was online and available, anyone could retrieve their figure code from that. Now that Universe is no longer available, there's currently no FREE way to get your figure code.
It was made known to me very recently that SWAP FORCE (any platform) allows you to retrieve your figure code. For more information see this support link:
I hope the Collection Vault supports a portal to eliminate the need to find codes, but as it stands now there's over 10 figures that won't scan into the application and needs to be fixed.