It is very likely that you have not performed all the post installations steps if you see the following error at Call adapter step:
The termination occurred in system <SID> with error code 403 and for the reason Forbidden
If <SID> is an ECC system, log on to the ECC system and call transaction SICF. Activate the sap/xi services to get rid of the errors.
If <SID> is XI/PI system: Run the ABAP report RSXMB_ACTIVATE_ICF_SERVICES
If you are using Web Dispatcher and maintaining a permissions table, ensure that the services are not blocked.
403 error are often misguided as user authentication errors causing the admins to reset passwords blindly. For authorization errors the return code would be 401.