The new element should come with fitting instructions. If it doesn’t come with an earth attachment, it should be a Class II fitting, and will have two concentric squares on it. If not, it is class I, and therefore needs to be earthed.
If I was doing the job, I’d be calling the technical support line at the manufacturer to get their correct advice. My *best guess* would be to secure the earth attachment to the part of the oven that surrounds the element. The oven should have good earth conductivity in all the exposed conductive parts. The oven should have a good earth as part of the electrical installation for the property. A sparky will check this at the time.
Note, the word ‘should’ is used specifically. Don’t assume it is true. If the oven is old and designed to have an earth on the element, it may still need one.