Question: how to download nwds from service marketplace?
Answer: Go to https://nwds.sap.com/swdc/downloads/updates/netweaver/nwds/nw/731/doc/auto_com.sap.netweaver.developerstudio.distributio… and log in with your SAP Marketplace login. Choose which version you need and download the SAP NetWeaver Developer Studio (I used the download for SP15 and PAT0000).