Rebuy Bundle Builder is the front end user interface that customer interact with to add recommended products as a bundle to their cart. This is typically used on the custom pages like Mix and Match, Bundle Set, etc. Although they can be installed automatically on any page, you can manually installing the bundle builder widget html div into the corresponding liquid file. (2.0 themes can use app blocks to accomplish this)
Rebuy Bundle Builder widget is built in Vue.js which allows them to be dynamic according to the data that they are provided. You can learn more about the helpful attributes in this Vue.js guide.