splunk analysis for hadoop is already included as part of Splunk Enterprise. You will get 60 days license once you download Splunk. The above add-on is just to request an additional license past the initial 60 days.
On the Splunk base link for Splunk Analytics for Hadoop (https://splunkbase.splunk.com/app/3311/) you will find the
Visite Site button instead of 'Download
button. Just click onVisit Site` button , the new tab will be open with below link.
Here you have to fill form by mentioning your details and purpose to Get Splunk Analytics for Hadoop.