Good afternoon Wendie and welcome to the Events Calendar Support forum!
Thank you for reaching out to us and for the system information.
We are sorry to hear about the jquery conflict on your install.
I would love to help you with this topic.
The most likely cause of the issue is that your theme, a customization or a plugin on your site is loading another version of jquery.
The fastest way to find out what the cause is would be to go through our testing for conflicts procedure (preferably in a staging/dev environment or local install of your WordPress website) and let us know what you find out.
Basically the goal here is to revert back to a bare WordPress installation to see if the problem persists. It also allows us to pinpoint what the cause of the issue is.
Additionally, I am noticing that you are running PHP 5.3x on your server. I would highly recommend upgrading to 5.4+ . There have been many reports of things breaking with 5.3 and below.
In fact, WordPress recommends 5.6+ (but 5.4+ should be fine for now).
Let me know how that goes.
Best regards,
Geoff B.