The SWID (SolarWinds Customer ID) is a unique company identifier for your company at SolarWinds. When logged into the portal, you will be able to see your company name and SWID at the top of the screen.
Rel: https://thwack.solarwinds.com/t5/Group-Archive/Frequently-Asked-Questions-about-Customer-Portal-accounts-and/gpm-p/189761#M466