Synthesis reaction: turn 4-octyne into butanal

[Lo.Lee.Ta.]

I know that first we have to add H2 and a Lindlar catalyst in order to produce what is the reactant.
I thought adding O3 would be an ozonolysis reaction.
An ozonolysis reaction should yield this:

I don't know why they added the Zn and CH3CO2H, though.

What does this even do in the reaction?

Thanks for your help! :)

 

[chemisttree]

What is the structure of the first-formed product of the double bond with ozone and what is the mechanism of the reaction?