How does bitcoin depot convert cash to cryptocurrencies?

Could you elaborate on the process involved in converting cash to cryptocurrencies through a Bitcoin depot? I'm particularly interested in understanding the steps a user would need to take and any potential intermediaries or systems that facilitate this transaction. Also, I'd like to know about the security measures employed to ensure the safety of the transaction and how the exchange rates are determined. Furthermore, are there any fees associated with this service, and how long does the entire process usually take? I'm keen to understand the intricacies of this process and how it enables the seamless integration of cash and digital currencies.