I’m suspecting something wrong happened during the instalation. Could you check if you can open the Face_Archetype skeletal mesh?
Do to this, in your Content Browser, make sure to have Engine Content and Plugin Content enabled:
Then navigate to Engine/Plugins/MetaHuman Content/Identity Template. In this folder you should see a Skeletal Mesh called Face_Archetype.
Are you able to open it? If you can open it, try to right-click and select Duplicate in the asset. Does it duplicate just fine?