Workplace will check to see if you have a password set for your user, as per your applicable security policy. This is to ensure that if someone physically gains access to your computer they cannot get into your account without your password. If Workplace indicates that this is turned off, it only takes a few clicks to turn it on.
In almost all versions of Windows, you can open the Control Panel and search for "password." Choose the appropriate result and it will bring you to the setting where you can add a password to your account in Windows.
On a Mac, open System Preferences and choose the "Security & Privacy" pane. Click the lock in the bottom left of the window to make changes in there you will find where to change your password.
If for some reason, you cannot set a password on your device to satisfy the device security check, you may be able to contact your local admin or IT support to grant you a one-time exception so you can continue on.
Once your account has a password, refresh the Workplace security checks page or go back to log into your portal and Workplace will indicate that you have passed the check and you can proceed!