When you upload a SCORM package, and you get an "This is not a valid SCORM file" error message, it's probably because your package isn't zipped right.
For a SCORM package to be properly imported into TalentLMS, the "imsmanifest.xml" file must reside in the root folder.
If instead of exporting your SCORM package directly into a zipped file, you export it into a folder, and then zip that folder and upload it to TalentLMS, the "imsmanifest.xml" cannot be found in the root of the zipped file.
In that case, all you have to do is:
1. Unzip the zipped file.
2. Open the unzipped folder (this should contain the "imsmanifest.xml" file).
3. Select all files and create a new zipped file.
4. Upload the new zipped file to TalentLMS.