This is the normal process:
To validate and apply for Rich Pins:
Choose any page on your site that you’ve added metadata to. Enter your chosen URL below and click Validate.
Correct any problems you see with your metadata. Select one of three options depending on how you marked up your page:
– HTML Tags, if you used Open Graph or Schema.org formats.
– oEmbed, if you used oEmbed format.
– Shopify, if you have a Shopify site.
Click Apply now. Your Rich Pins will show up within the hour.
Note: You only need to validate and click apply for one link on your site to enable Rich Pins across your whole domain.
But for me when I validate my URL and I go on my post page to select one of the tree options, I don’t find any. So I cant complete the process.