AppxPackage - developer license

[extromen13]

Hi,

when I am doing the second phase - register, I will always get following error

Add-AppxPackage : Deployment failed with HRESULT: 0x80073CFF, K instalaci této aplikace potřebujete vývojářskou licenci pro Windows nebo systém s povoleným zkušebním nač
ítáním aplikací (sideload).
Deployment of package Firefox_1.0.0.0_x64__zgke8crrmjz2e with package origin Unsigned failed because no valid license or sideloading policy could be applied. A developer
license (http://go.microsoft.com/fwlink/?LinkId=233074) or enterprise sideloading configuration (http://go.microsoft.com/fwlink/?LinkId=231020) may be required.
NOTE: For additional information, look for [ActivityId] e03c0518-0c46-0001-cc59-3fe0460cd801 in the Event Log or use the command line Get-AppPackageLog -ActivityID e03c0
518-0c46-0001-cc59-3fe0460cd801

I enabled developer mode and enabled running applications from all locations, but without any effect
Thank you