DASH is only available as part of the Cambridge Structural Database (CSD) software suites (available as part of CSD-Materials) which are released in November of each year. It is also possible to download data updates at regular intervals between each major release. For further information please compete the Information on obtaining CCDC products form here.
DASH will be moving out of the CSD Portfolio in late 2021 and will thereafter be available as an open source project on GitHub. See DASH Software - Moving To Open Source for more details.