Hubspot authentication is done using the environment variable "APP_HUBSPOT_TOKEN", which is generated by setting up a private app in your Hubspot instance. Read how to create a private app in the Hubspot documentation.
Forms can be inserted as content elements and will be rendered via the Hubspot Forms JS.
CTAs can be included as content elements anywhere on your web site.
The extension provides the possibility to add campaign tracking information to any page in TYPO3. The tracking information will thereafter be included in every link generated to that page by TYPO3.
The Hubspot integration backend module displays an overview of all used hubspot elements and where you can find them. For example if you need to know which forms are used where, use the forms overview.