Bottom
The bottom section of the template design (from Quickstart) was built using single SP Page Builder Module published on "bottom1" position.
Footer
Copyright note and "Designed by" was based on template settings feature. But of course you can publish your own modules in postion: footer1.
The Footer is a core template feature and it inherits all the functionalities from Helix Ultimate framework. You can make the customizations in your own way by understanding the framework better. You can head over to Helix Ultimate Documentation for further reference.