Hi,
 
TLDR
How to apply discount based on quantity of specific product category on those products only?
Like this https://docs.magento.com/m2/ee/user_guide/catalog/product-price-tier.html but for category.
 
I am trying to solve specific problem 
Customer has multiple categories (lets call them cat1, cat2 , cat3...) and each category contains different products (ex cat1 contains A,B,C,D...)
Requirement is for each product in category to apply discount on quantity .
 
Example:
- if user puts any variation of 10 products of cat1 (eg. 3 of A + 7 of B) in the cart he gets a discount of 10% on that products. 
- But if he puts 9 items from cat1 and 1 item from cat2 user doesn't get a discount .
- Or if he puts 10 items from cat1 and 1 item from cat2 user gets discount on cat1 products but not on total amount .
 
This is what i tried
1) I have tried this but its for specific product not a category of products
https://docs.magento.com/m2/ee/user_guide/catalog/product-price-tier.html
 
2) And in marketing > price cart rules 
I had created a rule based on product category but its applying on total quantity 
 
Thanks !