There are two ways to import a project archive (.spryzip) file back to LumaFusion.
1. If it's on a Cloud Drive, you should open the Project Manager in LumaFusion (tap on the Project Manager icon at the top left of the preview), tap on the import button at the bottom of the Project manager, and select the file to import. It should import and open that project, ready to edit.
2. If you have the file on a Mac, right-click on the File, select "Share" and pick "Airdrop". You can then Airdrop it to your iPad/iPhone, and it should open in LumaFusion.
If neither of these work, you could send us a link to the file on a cloud store to firstname.lastname@example.org
and we can try and determine why it's not working.