OAuth v2 Authentication

Hi,

I am struggling with authenticating my app with my Jira Account.
I created the Application link in Jira with my App and set up all the configurations.
I am then using the rest api client to get the request key and the access key:
https://developer.atlassian.com/jiradev/jira-apis/jira-rest-apis/jira-rest-api-tutorials/jira-rest-api-example-oauth-authentication

I am able to get the request key:
(upload://rxtfSo22YUCPqWLnlI6D0DKMhRa.png)

but when trying to get the access key I get different errors such as token rejected (when I click on the “Approve in the Link” ) or oauth_problem=permission_unknown.
I can’t find a lot of information and seem to be stuck on this problem for very long.
Is there anything that I am missing? What is the correct solution to get the secret_key without the user “Approving” the request in the link?

Thank you,