Composer Packages problem on fresh 27.1 installation
Okayyy... 😉
I had issues with the Packages Tiki Installer from the front end too.
If you have a shell access try with the console.php installer.
package
package:clearcache Deletes all content from Composer's cache directories.
package:disable Disable a Tiki Package
package:enable Enable a Tiki Package
package:install Install package
package:list List installed/available to install packages
package:remove Remove package
package:update Update package
It helped me in many cases.