If you encounter the 402 error enablePersonalization is not supported on this plan when sending search requests to Algolia, it means that Personalization is enabled for the Magento extension (via the Magento Admin) but the customer plan does not include the Personalization feature.
This setting can be updated in Algolia Search > Personalization tab of your Magento Admin and "Enable Personalization" should be set to "No" as show in the screenshot below.
If you receive this error but believe that the Personalization feature should be included with your plan, please contact Support so we can assist you.