Cant turn on Calls on other devices on my iphone x

Then read through the link I provided above, and make sure everything is set as it explains.

Note that Facetime activation may require an international SMS, so you may need to contact your carrier to allow this.

Can you tap on the "Use Your Apple ID for Facetime" message?

If you get an error when trying to activate iMessage or FaceTime - Apple Support

Tugedamos wrote:

It says that facetime and icloud must be signed in to the same apple id

And are they?

Settings->Facetime->Apple ID and Settings->Account(top of settings)