The 560 itself can't scan to Yosemite, but the Fiery can as long as you put a domain, even a fake one before the username.
You can't just use the "labuser" name because EFI requires a Domain, but "MSHOME" is just pretty much universal at this point and works fine as a placeholder so just use that.
For any combination of scanning I tried to 10.10 using a tempate and repository on the 560 itself the result was 027-516, which is a protocol error. Usually because of an SMB version that is not understood. On Server 2012 for instance it uses SMB3, the printer doesn't understand it so you need to allow SMB2 server side. This is as far as I know not an option on OSX. So for now, just use the Fiery templates instead.