Hi,
as you stated, you are currently running on 6.7.0.50000. So you can't update with the ISO of version 6.7.0.50000-18485166-patch-FP, because you're already running this specific version.
There is no newer release than 6.7.0.50000 to date - also see the vCenter versions list at https://kb.vmware.com/s/article/2143838.
If you want to upgrade your VCSA, follow the upgrade procedure as documented: https://docs.vmware.com/en/VMware-vSphere/7.0/com.vmware.vcenter.upgrade.doc/GUID-30485437-B107-42EC...
Regards,
Patrik