I have the same issue and get solved, you can see my thread How to use rest api in docker
To use rest api you have to either setup flowable-rest or flowable-task, to pass http basic authentication you can use something like
curl -i 'http://admin:test@localhost:8080/flowable-task/process-api/repository/deployments'
or
curl -i --user admin:test 'http://localhost:8080/flowable-task/process-api/repository/deployments'
You got redirected because you are using the application api which require cookie based authentication