A prototype-based development model is recommended because of the following factors:
Since the organization is non-computer based, the users are new to the system and have to be trained for even basic use of computer. So, everything should start small.
The initial prototype model will be based on the current manual activity and try to emulate the steps and processes.
After having user experience with the system, next level of enhancement shall be done and tested.
Such changes shall be gradually introduced so as not to frighten the users with complexity while making them increasingly comfortable with the new features.
This approach shall make sure that the users are almost fully familiar with the system by the time final prototype is made.
Moreover, users have greater sense of ownership as they are continually involved in the evolution of the system from initial prototype to the final functional system.