In order to configure or add new category rule in Magento 2 Dynamic Categories Extension navigate to Catalog > Dynamic Category > Rules.

Magento 2 Dynamic Category

Then, press the Add New Rule button to create a new category.

Magento 2 manage dynamic rules

New Category Rule

1. Set the Rule Name and add a Description if you want to, though this field is optional.

2. Enable Rule.

3. Assign the rule to the Web Sites.

Magento 2 new dynamic category rule

4. Enable Remove Other Products from Category if you want all previously added products to be removed and all new ones to be generated by the created rule.

5. Set the Category, you want the rule to be applied to.

6. In the Products section set the conditions under which products will be automatically added to the chosen categories.

Magento 2 dynamic category rules products

Once you have finished you will be notified about the successful rule creation and see it in the category rules grid. However, you also need to press the Apply Rule button in order for the rule to be applied immediately, otherwise you'll need to wait sometime to allow a cron script to apply rules and update categories products.

Magento 2 apply dynamic category rules