Navigate to Settings >> Design Settings >> Homepage >> Top Hero Section >> Search Box / Call to Action > Click on Select Call to Action.
Select the Display Button Links option:
This will activate the following fields:
Button Text: Add the text to be displayed. Example: Join Now
Button URL: Add the permalink that the button will link to. Example /join
Button Class: Choose the type of button.
This is what a homepage looks like when using three buttons:
