How to buy cryptocurrency using ACH?

Could you elaborate on the process of purchasing cryptocurrency using ACH? I'm particularly interested in the steps involved, from setting up an account to completing the transaction. Are there any specific requirements or prerequisites I need to meet? Additionally, what are the typical fees associated with using ACH for cryptocurrency purchases? I'd also like to know if there are any security considerations I should be aware of when making such transactions. Finally, how long does the entire process typically take from start to finish? I'd appreciate a clear and concise explanation of the ACH process for buying cryptocurrency.