Did you create the application user as ARAdmin? This is the database access user.
If you install the itsm, try to login the application with appadmin or Demo and set another pwd. The try to call you integration
I have not created the Application User as ARAdmin. It was my client who has created this User while AR System Installation. Is there any issue if we have ARAdmin as both Application and DB User?
No problem to use the same name as user admin and db user.
BTW, ask to you client to create a temp admi user (follow the steps in the link that I pasted), then access the application and change the ARAdmin pwd.