Hi @anilsp31,
The software package SW32K388_SBC_FS26_R21-11_3.0.0_CD01 supports EB Tresos, and does not support S32Ds, as shown in the release notes:

Please search instead for the "FS26 SBC AUTOSAR R21-11 Version 3.0.0" package, as this is the supported software for S32 Design Studio. The Design Studio supported version will come with a UpdateSite.zip file included.

Please follow the installation requirements for RTD version.

I hope you find this helpful.
Best regards,
Julián