Hello @jaygami
This seems to be a duplicate of the same question you asked in this thread.
In that thread you said “i have created one forge app deploy in jira instance”… but now you are saying “i didn’t know anything about forge setup”, which seems to be a contradiction. Also, you just said “i am using rails language” and, as far as I know, it’s not possible to create a Forge app with Ruby (on Rails).
As was advised in the other thread, when the API responds, “Only apps can access this resource,” it’s a reference to Atlassian Forge , Atlassian’s Cloud-hosted platform for building extensions.
The Get workflow transition rule configurations API endpoint is only available if you have built a Forge app.