Hello,
Enabling the allow_embed function to true is only available on Grafana Cloud Pro or Advanced tiers. It is not an available feature for Free. If you upgrade to Pro and want this enabled simply reach out to our Support team who can enable this for you.
Note that the embedded panels/dashboards will then be accessible only by those logged in to the hosted Grafana instance in the same browser. For security reasons we don’t enable public viewer (anonymous_access) on a hosted Grafana instance regardless of the tier you’re on. You can read more about the security implications of the anonymous feature here: Security | Grafana Labs