The passage is taken from the letter of Augustine to Fabiola, a noble Roman who offered hospitality and help to Antoninus. Antoninus, a young lector of the church of Hippo was ordained bishop of Fussala when the original candidate drew back (see [399]). Antoninus was later accused of several crimes. Augustine and his colleagues tried to make him step down, but he appealed to Rome. Fussala used to to be a Donatist see, so the date of the event is between AD 411 (the conference of Carthage) and AD 419 (the recourse of Antoninus to Rome).
The status of the presbyter in question is unclear: he was a notarius of Augustine and later a monk in his monastery. He came from some place other than Hippo. Probably, the presbyterial ordination was the first he received.