How to apply for ACH?

Could you elaborate on the process for applying for Automated Clearing House (ACH) services? I'm curious about the initial steps required to initiate the application process, as well as any specific documents or information that might be necessary. Additionally, I'd like to know if there are any eligibility criteria or fees associated with obtaining ACH capabilities. Could you provide a general overview of the timeline for approval and activation? I'm interested in understanding the overall process and any potential challenges or considerations I should be aware of before applying.