Thanks for posting on the forum.
Please could you try the following:
1) Ensure that all Microsoft Updates have been installed.
2) Any antivirus installed (other than Microsoft Defender) may needed to be stopped or removed (if free). Preferably, antirivus should be completely removed. Then you should uninstall your current CostX and re-apply for a new serial number (since each number can only be activated once), then install costX again.
3) Use the right click on the installer file and use “Run as Administrator” for the install.
If this still does not work, please could you provide us (email@example.com) with the log files which is in path: C:\ProgramData\Exactal\Logs – be aware this is a hidden path but you can also get to it via their Windows start button => RIB => iTWO costX => Shortcut to Logs. This will help us to help us identify and narrow down where the problem is with a student installation of v6.9.
iTWO costX Student Forum