Error: Empty Authorization header

Hello, when I try to interact with the API, I get this error.

  1. I created a LIVE application.
  2. Created a Rest API key.
    API I want to connect with Google Apps application. Sent a request with the following code:
    const url = “https://api.company-information.service.gov.uk/search/companies
    const api_key = Utilities.base64Encode(“a9b0cfcb-a88d-4a53-8276-61d6c9ebda67:”)
    const params = {
    method: ‘GET’,
    muteHttpExceptions: true
    header: {
    “Authorization”: “Basic” + api_key
    }
    }
    const req = UrlFetchApp.fetch(url, params)
    let res = JSON.stringify(req.getContentText())

The result of running this code:
5

Also, I tried to make a curl request as in the example:

I tried to create a Streaming API key and even connect via Oauth2, the result is the same.

Please tell me what could be the problem?