How to edit interactive "properties for sale" map

I’m trying to edit a section on the following webpage:

https://edengardensepping.com.au/now-selling

I am new to Craft and this has been a website handed to us to be updated after being built by someone else,

In the second section of this webpage there is an interactive map which I am wanting to edit (see image attached if you are unsure of what I mean):

Does anyone know how they have built this, is it a plugin?
Within Craft they have been using a plugin called Field Manager,

Below is what I need to edit on the map:

1. I need to edit the background part that is not interactive and upload a new file to replace the one in there with updated information
2. I need to change the background colour of the sold lots which currently have a red dot on them
3. I need to remove the text that says "High Park Release" and also the background