Missing prefabs in Nuitrack Unity package


I have a problem with the newest release of Nuitrack SDK. When I tried import Unity package, I got many errors about missing prefabs (screenshot below). After a few attempts, the problem repeats itself. I tried on Unity 2019.4.18f1, 2017.4.40f1 and 2020.3.22f1, same problem everytime.

Have you any idea where the problem may be?

Thank you in advance for your help.

If there are any errors after that. Just click “clear”, everything should work