It would appear that the 6.7 Delta exam is only for those who already hold VCP6.5-DCV, and not any earlier VCP-DCV version.
Exam options for VCP6-DCV holder to achieve VCP-DCV 2019:
Exam options for VCP6.5-DCV holder to achieve VCP-DCV 2019:
The outcome from either of the above would be the same anyway - recertify your existing VCP (6 or 6.5) and achieve VCP-DCV 2019.
That is respected, VCP6-DCV > VCP-DCV 2019 (coming forward 2 versions) by passing a single exam - it just can’t be the delta exam, it has to be the full one.
I haven’t investigated the detail of the delta exam, presumably it tests on differences between 6.5 and 6.7 (rather than 6.0 and 6.7)
Now when I looked 6.7 Delta exam blueprint there was also "The minimally qualified candidate (MQC) has already achieved the VCP 6.5- DCV certification"
To harmonize in that page there should also be "Pass one of the Professional Data Center Virtualization Exams" instead of "Pass the Professional Data Center Virtualization Exam" when you select "an active VCP5 of VCP6-DCV"