The plan might, for example, call for doubling the amount of roads, sewers and port facilities over a 5 year period, and would allocate the money for this. However, it was private companies who bid for the actual work. Furthermore, companies were free to carry out their own independent activities regardless of the bigger plan.
These are just ideas meant to form a starting point for a debate about what sort of system we could create to allow us to successfully navigate into the future. It is not a final plan. Nor is it a plan for a single central world government. Many competing corporations, governments, charities, foundations, etc. could all work in harmony with the future planning agency.