SAP Leonardo IoT has an improved version of the Launchpad/Launchpage. The Launchpad/Launchpage you were trying to open is not supported anymore.
Please have your global account administrator login to the cloud platform cockpit at to access the correct link provided to you. It can be found in your cloud foundry subaccount under "Subscriptions" for "SAP Leonardo IoT" labeled as "Go to Application" and looks similar to this:
For more details please refer to the following blog: