Yes. The ACF Pro bundled with HomeRunner is a full copy, so you can use it to build your own field groups and page templates.
What you can do. The Custom Fields screen in wp-admin is available for your own field groups, including repeaters, flexible content, and options pages. Page builders such as Divi can pick up those fields as dynamic content. There is no license key to enter on your side, and updates arrive with HomeRunner plugin updates.
Do not install a separate ACF plugin. Do not install a separate Advanced Custom Fields plugin (free or Pro) alongside HomeRunner. It replaces the bundled copy and can break HomeRunner’s photo syncing.
Your fields and HomeRunner’s fields. Your own field groups are stored in the database and appear in the Custom Fields list. HomeRunner’s property fields are registered in code and do not appear there, so there is nothing of HomeRunner’s to accidentally edit.