Checkbox if other => possibility to type text

I am creating a form. Clients can – via checkboxes – choose between 2 time slots during a week. A third checkbox, will be ‘other’. When choosing ‘other’, those who are filling out the form should be albe to type there prefered time slot.

How can I achieve this (possibility of typing a text when choosing ‘other’) with Fluent forms?

I am using the free version.