During the installation of Skyline, the user "Everyone" is given full access to the installation directory C:\Skyline. This does not mean that "Anyone" can access this directory. The Windows user "Everyone" is a user group that includes the users ASP.NET and the IIS anonymous user account. If required you can remove the user group "Everyone" and replace it with the users ASP.NET and Internet Guest Account.
The actual name of the IIS anonymous user account contains the machine name e.g. IUSR_PCNAME. The Skyline installation program needs to set the permissions of C:\Skyline to allow the user accounts ASP.NET and IUSR_PCNAME full access, but since we can't know in advance the actual name of the IIS anonymous user account, it has to use the user group "Everyone".