In the past a letter would be read (from the society) suggesting a certain amount to be contributed (per publisher) for a specific event or need. Publishers would then raise their hands in agreement, if the majority agreed then the congregation would contribute that said amount to the society according to the number of publishers in the congregation. I would assume this worked on the same principle.
In order for a publisher to attend he had to make a "contribution" of R20.
If there was a ticket it would be admitting one had to pay to attend the zone visit.