A lot of CS0234 and CS0576 errors when importing

Hi, 
I'm getting a lot of the following errors when importing the sdk core (v1.2.1) into my project. I am using Unity version 2020.1.4f1.  
<img width="1159" alt="Skärmavbild 2020-09-28 kl  11 27 54" src="https://user-images.githubusercontent.com/33425634/94415822-5cd67e00-017e-11eb-8c9e-e4155af766f2.png">
