Configuring preferences and options in Outlook.com
I am not sure if anyone has shared a solution yet but I figured it out.
Open your calendar in outlook. Then go to the folder where the ICS file is and Open With the New Outlook. It should automatically open the Add Calendar screen on the Upload from File section. There you can select the file from Browse or drag and drop the ICS.
Additionally, you can just click Add Calendar and select the Upload from File option on the left side of the screen. Then upload the ICS file.
It imports it directly to the calendar without giving the option to edit first, so you will need to find the even in the calendar if you want to edit it. Annoying but the best option I have been able to find.