Sibeluis Trial installation problem

[Hulabalooo]

Hi there, I downloaded the free trial of Sibeluis this afternoon and have successfully installed it onto my MacBook (13-inch, Mid 2010) which has the OS X El Capitan Version 10.11.6 software. However, when I open the programme, a window opens with four options:

1. Buy Online
2. Activate
3. Continue Trial
4. Specify Licence Server

As I am only interested in the free trial for the time being, I select the 3rd option only for another window to appear stating that: "Sibelius wants to make changes. Enter your password...' So, I enter my password only for the programme to then quit. I have been looking through online forums but can't find a solution to my current problem. After spending most of the afternoon trying to get Sibelius to work on my machine, I do not want to have to buy a subscription only to find out that it won't work, as well as still being entitled to 30 days of the free trial. I am also not entirely convinced I would want to buy Sibelius after all the stress it has caused. If someone could help me, I would be very grateful.