I was trying to get access token with oauth 1.0 but getting Invalid signature for signature method HMAC-SHA1. I have the request token and verifier.

Api i want to integrate:
https://api.immobilienscout24.de/api-docs/authentication/three-legged/

$consumerKey = "myrealapiKey";
$consumerSecret = "wEBxKUuQWYqRQ0Kb";