If you get an error such as "The zip does not contain the files needed..." or "Missing manifest file..." when you try to upload a published Gomo course to your LMS, then it is probably because you have published the course from Gomo using Safari on a Mac. By default, Safari will automatically open certain known file types, including zip files. If you then zip up the folder it creates rather than the contents of that folder then, when that file is uploaded to an LMS, the LMS can't find files like the imsmanifest.xml file since they are contained within a subfolder, hence the LMS error message.
To fix this, you can either make sure you open up the folder which Safari creates and zip its contents, or you can stop Safari automatically opening the zip file as follows:
In the menu bar, click on Safari -> Preferences. In the General tab, uncheck Open "safe" files after downloading:
This will stop Safari from automatically unzipping the files. You can then republish the course in gomo and download it and you should just end up with a zip file in your download folder ready for uploading to your LMS