(SOLVED)
Hi all,
I was trying to understand the document on this page on where to assign an enemy spawn group to a tile group:
https://rpginabox.com/docs/doku.php?id=combat_editor&s[]=enemy&s[]=spawn
If anyone else is looking for it, it is located here in the map properties section.
As I always kept selecting a tile to create a tile group, I was missing the options because I would always have a tile already selected.
Thanks @thomas for the help!