answer from HERE Support rep:
Hi Marc
Thank you for reaching out. We have a technical issue that’s preventing us from offering the HERE apps in the Windows Store for new Windows and Windows Phone 8, 8.1 and 10 users. We are working to resolve the problem and restore the availability of the HERE apps for new users. Until it’s resolved, we recommend that new users take advantage of the pre-loaded Windows Maps application on their Windows operated device. If you already have the HERE apps on your Windows 8 or 8.1 device, then you should continue to receive updates and see the HERE apps available in the Windows store. Until we have a resolution, we recommend that you do not delete the apps from your device.
You can try going to the store -> account-> my apps, if it is not there, then you have to wait for the fix update that will take some time because it involves both HERE and Microsoft to fix it.
In the mean time you can use here.com or m.here.com for some basic route calculations. Sorry for the inconvenience.
Best regards,
On the behalf of the HERE support team