The image of a bank employee up a ladder comes straight from the box art for this set. While a man scrubs away at the bank's clock, the bank manager is standing on the pavement trying to hand him an envelope. Very strange. In this image, it is the administrator argentarius himself doing the heavy lifting. For whatever reason, our Augustus, whom I assume to be a very busy man, can be found in the middle of the afternoon up a high ladder ensuring that the town's timepiece sparkles in the sun.
argentarius is an adjective meaning 'of or concerned with silver; monetary, financial, pecuniary, concerned with banking'. It is also used as a noun in the masculine meaning 'banker'. It comes, of course, from the Latin word for silver, argentum, which gives us both its chemical symbol - Ag - and the name Argentina, from the belief that the region was rich with that metal. I will translate administrator argentarius as the rather prosaic 'bank manager'.
Do you see Augustus? Augustus is the bank manager. At this time (ablative of time when) Augustus is standing on a high ladder, washing the clock.