You must be logged into a non-Columbia gmail account for creating custom maps; your Lionmail UNI / Password will not work.
As described above, select Add Map Location when entering content.
Locate and copy the embed code for your custom map.
When logged into your non-Columbia gmail account, go to Google My Maps.
Click SHARE for the map you want to embed.
Click <> Embed on my site.
Highlight and copy the mid code.
Back on your Columbia Site, paste the mid code into the Google My Maps ID field.
NOTE: You must also enter latitude and longitude coordinates as described above. Use an address in the center of your custom map to serve as your coordinates.