Error: Invalid host key (ServerShield from Cloudflare)

Hello,
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.
JC

That sounds like it needs a Partner Hosting API Key:
https://support.cloudflare.com/hc/en-us/articles/200168476-Where-can-I-find-the-Partner-API-key-