Hello Margaret,
Here are some troubleshooting things to try:
1. Check if your plugin is installed.
2. Check if your plugin is enabled.
3. Check if the jumi syntax is in an article and not in the category/section description.
4. Check if the code is visible.
Verify the plugin syntax {jumi [templates/iwc/events_alumni.php] } in no wysiwyg editor. Remove all unvisible characters from the syntax, if there are any.
Sometimes it helps, if you have more 3rd party plugins installed, if you move jumi plugin up in the list of installed plugins (plugin manager).
Also,
Go to your plugin list and find your Jumi plugin.
On your plugin edit screen from the top left, you will see labels in the order as below :
Name:
Enabled:
Type:
Plugin File: ( make sure the word entered in this field is jumi )
(there is no need to enter the .php extension as you will see it's already labeled on the right of the field.)