AWS 'eb init' not a valid key=value pair (missing equal-sign) Bitbucket pipelines

[admin]

I am setting up Bitbucket pipeline for a Wordpress deployment on Elastic Beanstalk.
This error message pops up in line

eb init --region AWS_DEFAULT_REGION --platform php-5.5

:

ERROR: ServiceError - '/20200712/$AWS_DEFAULT_REGION/elasticbeanstalk/aws4_request' not a valid key=value pair (missing equal-sign) in Authorization header: 'AWS4-HMAC-SHA256 Credential=$AWS_ACCESS_KEY_ID/20200712/$AWS_DEFAULT_REGION/elasticbeanstalk/aws4_request, SignedHeaders=content-type;host;x-amz-content-sha256;x-amz-date, Signature=3d7fef....8383d5'.

Other relevant questions and why it doesn't solve my problem :
<ul>
<li><a href="https://stackoverflow.com/questions/37902100/ws-eb-init-missing-equal-sign-error">1</a> <a href="https://stackoverflow.com/questions...lue-pair-missing-equal-sign/58080703#58080703">2</a> : Don't have /.aws/config in Bitbucket environment</li>
<li><a href="https://stackoverflow.com/questions/48692554/how-to-use-eb-init-without-manual-instructions">3</a> : Error message mentioned above</li>
</ul>
The Bitbucket pipeline till now :

image: tyrellsys/aws-ebcli

pipelines:
  branches:
    master:
      - step:
          script:
            - export AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID
            - export AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY
            - export AWS_DEFAULT_REGION=$AWS_DEFAULT_REGION
            - export APPLICATION_NAME=$APPLICATION_NAME
            - export ENVIRONMENT_NAME=$ENVIRONMENT_NAME
            - eb init --region ap-southeast-1 --platform php-5.5
            - eb deploy wordpress-beanstalk