Error, not logged in (5.6)

Hello,

I was struggling with the same issue and just tried something that worked fine. When you open the metahuman editor, Click on Metahuman Character tap and select Save Face Textures or Export options.

It will take you to the MetaHuman Consent page. Just click on Agree and the issue should be solved.

Please try and let me know if this works with you.

Best of luck.