The package fails to install, even though I have a valid/unused license

Have you just assigned or transferred a license to the domain? Then you will be unable of using the package from the old license/domain because that includes an older license key which is no longer valid. To resolve that, you'll need to either update to a newer version (if available), or do a force remove of the package and then download the latest version again.

In some cases, removing the core/components/PACKAGE/.pubkey file helps. This sometimes contains a cached license key, and after removing it the next license check or package installation will put in place the proper one.

If you still cannot install the package, please make sure your server meets the minimum server requirements and check the installation log for detailed information. Get in touch if you need help.