Hi Anusha,
As this seems to be DTR authorization issue, I would recommend you to please check if your user has sufficient authorizations to perform any task in DTR.
For this, please go through the below help URL:
https://help.sap.com/saphelp_nw70/helpdata/en/c9/d94388f62c8f478eadd4d1902d7101/content.htm
Hopefully, after checking and verifying the required privileges granted to the user, your issue would be resolved. Please ask your BASIS team to carefully check if all the required privileges have been granted to the user.
BR,
Anurag