First thing to know is that suitescript api’s represent binary data as base64, so your data is probably more useful in base64 form. For example, you can use N/file to create a zip file in NetSuite’s file cabinet while keeping the contents bas64 encoded.

Second thing is that using N/encode or that suiteanswer artile is a mistake, it converts the base64 encoded string into an actual plain text string. Thats wrong, your data isnt plain text. At best, you want a library that implements atob or btoa, which are functions designed to work with binary data.

Third is that suitescript by itself will not get you to unzipping the zip file. The only compression related module is N/compress, which doesn’t actually support unzipping. Theoretically you can find compression libraries on npm that you can get working suitescript, but the performance is bad and you risk hitting execution count limits. I simply recommend doing your integration on your own server and integrate the results of that with NetSuite instead.