Zip split is some weird utilty that splits the file into parts (like the split command).
Splitting a file
Simple command interface
zipsplit -n 1024 Large.zip
Will split the file Large.zip into 1024 byte chunks.
This seems more complex than is you used split.
Make a Large file
Like split - cat it all into one file
cat img.zip.0* > img.zip
Fix the file
Not sure why this is needed but it is.
zip -FF img.zip --out img_fixed.zip