The application ran your source text through the Inform 7 compiler, as usual, and then manufactured the final story file using Inform 6: all of this worked fine. However, the "cblorb" packaging tool then failed to make the actual release of the data out of your project. Its errors are written out on the Progress tab.

This almost never happens in normal usage, and is almost certainly the result of a "Release along with..." sentence in the source having asked to do something impossible. For instance, an attempt to release along with cover art will fail if there's no cover art provided, or it has the wrong filename or is in the wrong place. So the best thing to do is probably to look carefully at any Release instructions in the source, and check them against the documentation.