Good find - how big is it? 3 adult Khakis will need approximately 18 sq ft of space minimum, and that's if they are only in there at night.
Otherwise I do see two fixable issues.
1. The ladder (soon to be ramp?) Looks way too steep for ducks - it will need to be a much shallower angle. Ducks do not typically do very well walking up steep ramps. It will also need something to prevent them falling off the sides of the ramp - a duck's legs are quite fragile.
2. The chicken wire floor is likely going to be a foot injury source, ie: bumblefoot and catching of the toe nails. I'd recommend perforated rubber floor matting over top of the wire, still allows for easy cleaning and is much safer on their webbed feet.
I've read in many places that ducks need anywhere from 2-10sq ft per duck at night (depending upon the source). I prefer to go with a minimum of 6sq ft - this allows them to move about and stretch their wings (I have a live cam set up in my ducks' barn - and they are much more active at night than you might think).
If you ask a milk cow farmer how much space each of his cows need, he'll say acres - but if you ask a veal producer how much space a calf needs - he'll tell you they are fine in the tiny pen they are kept in - it depends on your end goal.
As 'pets', mine have as much space as I can realistically provide at night - for example, my 5 ducks (3 Welsh Harlequin ducks, a Khaki Campbell duck and a Pekin drake) have an enclosed 'night barn' that is 5'x6', or 30sq ft/ 6sq ft per duck - HOWEVER - their night barn opens up through a door to a fully predator proofed, enclosed pen which is an additional 8'x9' (72sq ft /14+sq ft per duck), and they have open access to the pen from the night barn at all times. As noted that is simply my example.
If you only plan on having them in there at night, it may well be OK - however, it really sounds to me like it might to be too small an area for them - but only you, and time will tell. If you find them picking at each other (bald spots, pulled feathers in the pen, etc) it's too small, and you'll need to expand