Tried to install the universal forwarder for Spunk Cloud trial. In my welcome email the URL I received was (https://prd-p-26gtz8wkgkth.cloud.splunk.com). So for the deployment server I put (input-prd-p-26gtz8wkgkth.cloud.splunk.com) and port number 8089. I tried to install but I received a "You do not have sufficient privileges to complete this installation error".
Sounds like something you'd see when attempting the windows install, but @mayurr98's question is still valid: did you try this as the admin user (irrespective of which OS it is)?
