WAS v9 can be downloaded via IBM Installation Manager.
For developers see
https://developer.ibm.com/wasdev/downloads/#asset/WAS_traditional_for_Developers
For ND you can find the download links at
https://www.ibm.com/support/knowledgecenter/SSEQTP_9.0.0/com.ibm.websphere.installation.base.doc/ae/cins_repositories.html