Configuration 

Include the site set 

This extension comes with a site set called jambagecom/agency-default-plugin-set. To use it include this set in your site configuration via

config/sites/my-site/config.yaml (diff) 
 base: 'https://example.com/'
 rootPageId: 1
+dependencies:
+  - jambagecom/agency-default-plugin-set
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See also: TYPO3 Explained, Using a site set as dependency in a site.