Answer:
The user must have the read and write permissions for the destination folder. This folder is specified in the error message (see Image 01).
Please set the required permissions to this folder. To do this, select the folder and open its properties. In the "Security" tab, you can then, for example, set full access for the "Users" group or for the selected users (see Image 02).
Now, it should be possible to import the license file. The required user rights can also be found in the User Rights document that is available under Downloads below.
As an alternative, you can start the program as an administrator using the "Run as Administrator" command in the shortcut menu of the program icon (see Image 03). Then, import the current license file.