How can I add a confirmation popup to my checkout page?

[itslaura123]

I want to add a popup (ideally to the checkout page) that requires the customers to click 'confirm' or 'agree'. The checkbox text would be something like 'Shipping delayed: orders placed between XXX to XXX will be shipped after XXX'. Upon clicking 'agree', customers can proceed with the payment, otherwise they will not be able to make payment.

Does anyone know how to do this without installing an app?

Theme: Dawn 10.0.0

Thank you in advance!

My store URL: www.perfectshift.com.au 

[itslaura123]

It's 3 months since going live

[itslaura123]

My question was posted only half an hour ago, it's not resolved. And how do my sales and traffic have anything to do with my question?