Error: Invalid host key (ServerShield from Cloudflare)

I’m trying to #activate my CloudFlare ServerShield account from my Plesk in my hosting at hostForLife.
Can not connect, I still have the message:
Error: Invalid host key.
I tried to create an account directly at CloudFlare, but I still can not start CloudFlare from my Plesk
Someone would have any idea ?
Thank you in advance.

That sounds like it needs a Partner Hosting API Key: