Generating Auth Token

I'm trying to generate access token by calling the endpoint but it gives an error
Here is my command:
curl --location --request POST --url 'https://auth.accounts.poap.xyz/oauth/token' --header "Content-Type: application/json" -d '{"audience": "https://api.poap.tech", "grant_type": "client_credentials", "client_id": "my_client_id", "client_secret": "my_client_secret"}'