How to accept crypto payments on WHMCS website?

Could you please explain in detail the steps involved in accepting cryptocurrency payments on a WHMCS website? What are the necessary preparations and configurations that need to be made? Are there any specific requirements or limitations that I should be aware of? Additionally, how secure is the process of accepting crypto payments through WHMCS, and what measures can be taken to ensure the safety of transactions? Lastly, are there any fees associated with using cryptocurrency as a payment method on WHMCS, and if so, how are they calculated?