Request for StorefrontAccessToken returns 403

[Hewrin]

Hi, I'm using the shopify_api gem to request a StorefrontAccessToken but I keep getting a Forbidden response

ShopifyAPI::StorefrontAccessToken.create(title: 'Test')
Response code = 403. Response message = Forbidden.

I have set my scopes as below:

config.scope = "write_content, unauthenticated_read_content, unauthenticated_read_collection_listings"

Any idea what I did wrong?

Best Regards
Faris