How many birds is this intended to house?
You need A LOT more ventilation. The plastic covers over the vents won't stop anything from chewing through if they can get up there. I guess that's one advantage of a resin shed: it's slippery.
That's also an extremely small run with no protection from...
As long as the gaps are less than 1/2" don't worry about them. It's good ventilation.
You undoubtedly will need to add much more ventilation.
Please provide pictures for suggestions on how and where to add it.