Implementing Ueberauth GitLab

I am trying to implement GitLab OAuth.

Here are two packages I found from Hex.

After setting up, I get this error.

Server responded with status: 401

Headers:
server: nginx
date: Fri, 13 Jul 2018 04:16:49 GMT
content-type: application/json; charset=utf-8
content-length: 162
cache-control: no-store
pragma: no-cache
www-authenticate: Bearer realm="Doorkeeper", error="invalid_request", error_description="The request 
is missing a required parameter, includes an unsupported parameter value, or is otherwise malformed."
x-content-type-options: nosniff
x-frame-options: SAMEORIGIN
x-request-id: 53dd14b8-3bb9-43b3-839f-ac900ab288c7
x-runtime: 0.037092
x-xss-protection: 1; mode=block
content-security-policy: object-src 'none'; worker-src https://assets.gitlab-static.net https://gitlab.com blob:; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://assets.gitlab-static.net https://www.google.com/recaptcha/ https://www.gstatic.com/recaptcha/ https://apis.google.com; style-src 'self' 'unsafe-inline' https://assets.gitlab-static.net; img-src * data: blob:; frame-src 'self' https://www.google.com/recaptcha/ https://content.googleapis.com https://content-compute.googleapis.com https://content-cloudbilling.googleapis.com https://content-cloudresourcemanager.googleapis.com; frame-ancestors 'self'; connect-src 'self' https://assets.gitlab-static.net wss://gitlab.com https://sentry.gitlap.com https://customers.gitlab.com; report-uri https://sentry-infra.gitlap.com/api/3/csp-report/?sentry_key=a664fdde83424b43a991f25fa7c78987

Body:
%{"error" => "invalid_request", "error_description" => "The request is missing a required parameter, 
includes an unsupported parameter value, or is otherwise malformed."}

Do I need to make changes in the package? Or am I setting up the deps wrongly? Or is it due to version conflicts?