A booking on the website is binding
Once you have booked on the website, it is binding. Failure to pay your deposit is not considered a cancellation. Cancelling without cancellation insurance is then only possible with costs (after 24 hours) or by finding someone to take over your travel package.

Your cancellation file is only started when you have paid at least a sufficient travel balance to cover the applicable cancellation fees. Until then, no cancellation file is created. This is important, because as long as no cancellation file is created, the clock is ticking and you will soon find yourself in a higher scale of cancellation fees. Something we both want to avoid at all times, so don't lose sight of this!

More information regarding these topics can be found here:
Substitute for my cancellation
Start cancellation + info costs / refund