Open Keycloak
Select or Create a new Realm in KeyCloak
Copy the link pointing to the SAML 2.0 Identity Provider Metadata
This is a url : <keycloak-url>/auth/realms/<realm-name>/protocol/saml/descriptor
Open the Atlassian Application
Select the URL option as Identity Provider and paste the in the link
and press on Save
Copy the SP XML and create a new File e.g. sp.xml and paste the content in this file
If you don't see the SP Certificate, log out and log in again