Select the “New to VMware Certifications” option on the left of this page and expand Step 1 for details: https://www.vmware.com/learning/certification/vcta-dcv.html

The training isn’t mandatory though, how you gain the knowledge needed to pass the exam is up to you.

Select the exam under Step 2 of the page above and you’ll find the exam guide which tells you all the topics you’ll be tested on.

But where is the knowledge modules, where are the questions? they have it for 6.7

What do you mean by "knowledge modules" and "questions"?

VCTA only launched in late 2020, long after the release of vSphere 7, not sure what 6.7 items you are referring to.

I think I found the issue.  

Look at the screenshot from the video announcing the free 55 x 15min VCTA training videos on learningconnect...

It was a promotion that ended. When you search for VCTA now, you find nothing for free.

You weren't going mad mate! 

Current promotions are always posted here: https://www.vmware.com/learning/training/certification-special-offers-beta-classes.html

Not sure where $4000 comes from, the Premium Subscription is $269: https://store-us.vmware.com/vmware-customer-connect-learning-premium-subscription-5343779800.html