If you have HALion 5 you should go for the Update from HALion 5 to HALion 6.
In Cubase there is only HALion Sonic SE which does not qualify for the update. But HALion 6 also includes HALion Sonic 3. So, the HALion 6 update should be your choice. Please get in touch with the support to cancel your order and get a new license.