ERROR: Please perform this installation as system administrator

[natalia]

I have followed the installation instructions but I get this message after I attempt to install the ATCOR 23 programme.
'The installation directory:
C:\Program Files\ReSe_Software_Win64\IDL87
is not writeable for you.
Please perform this installation as system administrator and make sure the installation directories are writeable.'

The Windows 'Programs' directory is not always writable for non-admin users.

So, the software is either to be installed by a sysadmin or you place the whole installer anywhere outside of the Programs directory and start it from there.