The message you are receiving comes from your computer system and not from the software. Although you have an administrator's account it is possible that your school's IT department has placed restrictions on installing new software. It is also possible that the issue is specific to the trial version of the program as it requires internet access to be able to check its license (and this may be prevented by school firewall settings etc).
Please contact your school IT support who will be able to make an adjustment to your security settings or install the software for you.
Another solution is to try the trial version at home on a non school computer.
If you continue to experience difficulties, please contact us!