eChecks can take up to 6 days to clear and settle into your bank account. The Payment Txn will have a status of "eCheck Pending" until it is settled.
When the daily Recurring Payment Processor finishes, a second process is started that checks Authorize.net for transactions over the last 7 days to see if the transaction have settled successfully or not. The Payment Txn status is updated to "Payment Complete" if the transaction was successful and "Error" if it was not. The transaction check processor also updates the Payment Txn field "Settlement Date/Time" and assigns the Authorize.net Batch Id to "Payer Id" field.
For more on Authorize.net eCheck settlements, see How does the eCheck.Net settlement process work?
Please see the FAQ Above "When do eChecks's settle".
The Recurring Payment Process MUST be started, even if you are not using Recurring Payments. The Recurring Payment Processor when finished then triggers another processor that checks for eChecks being settled and will then mark the transactions as Payment Complete or Error.
See FAQ on starting batch processors (but select the one for "Recurring Payment Processor")