"package manifest contains invalid XML"

Was this ZIP file created directly by Captivate when you published with the ZIP option checked? Or, did you select the published folder and compress it yourself?  There can be a big difference in the result.

When Captivate zips the published output the imsmanifest.xml file is at the root level of the zip archive.  If you just select the folder containing the published output and compress it, the manifest file ends up being one level lower in the hierarchy and the LMS cannot find because it expects the manifest to be right at the top level.

So, if it was you and not Captivate that created the zip, just let Captivate do it.  

If you have a reason for NOT letting Captivate automatically create the zip file (e.g. you had to include some extra files in the output) the trick is NOT to select the outer folder but to go INSIDE the publish folder, select everything, and then zip the contents.  That way the manifest will be at the right level for the LMS to find it.

CP2019 is the common name for 3 main releases (11.0, 11.5 and 11.8) ad multiple patch releases. Please tell which version you are using exactly. The full version number can be found under Help, About Captivate.

Publishing to SWF has no sense anymore since multiple years because the Flash player has been banned everywhere.

You first need to find out if the problem is due to CP or to the LMS. Did you test on SCORM Cloud to figure that out?