Unless you're spending an arm and a leg on high-end furniture, trying to assemble prepackaged parts that are supposed to resemble a couch you bought is pretty much futile. Either the instructions are difficult to understand, none of the pieces fit correctly, or there are missing parts. Why put yourself through the hassle of building a poorly designed, mass-produced piece of furniture when it won't even turn out right? Instead of wasting your time, you could build something like this, instead
Cut a few logs into smaller slabs and glue them to the top of the plywood box. Try to line them up with the birch logs around the outside.
The grout will help give your coffee table a more even surface (and it will make the wood rounds look like full logs).