Try using the Add/Remove Programs tool from Windows to remove any existing version of BandLab Assistant or Cakewalk by BandLab that appears. You can keep any older versions of SONAR if you have them, just remember to choose Do Not Remove Shared Folders if uninstalling any versions.
After, you can follow this link to install the latest version of Cakewalk by BandLab.
This version will activate and provide updates directly within the program itself, so you will not need to use BandLab Assistant moving forward. Simply follow the link to get the latest version! After, right-click the desktop icon and choose Run as Administrator, and enter your BandLab credentials when prompted. This will activate the program for use. To keep the program activated, we advise updating at least once every six months. If you choose not to update your version of Cakewalk by BandLab, open the program and choose Help > Refresh Activation.