const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    authEmail: 'jsmith@example.com',
    otp: '<string>',
    marketingCampaign: '<string>',
    partnerId: '<string>'
  })
};

fetch('https://api.gnosispay.com/api/v1/auth/signup', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "id": "<string>",
  "token": "<string>",
  "hasSignedUp": true
}