Hi ACoonfield , I'm sorry to hear that and welcome to our forum.
In that case, please uninstall Enscape once more, then reboot the machine, run the Enscape installer again and in the first window of the installation process, where you will see the checkbox named 'I accept the terms in the License Agreement' make sure that is checked. This will enable the Advanced button which you should then click to proceed to the next window which will offer you the option to install for all users of the machine.
Please also make sure you're using our latest release Enscape 2.7.1, which you may already, but just to make sure since you've only mentioned 2.7.
Should that not be helpful, please let the user send in a feedback report with a link to this thread in the submission form, or a short explanation of the problem - this will allow us to then troubleshoot the cause behind this issue.