Here is another plugin I made that works with another system TREB has that (apparently) needs less paperwork. I’ve seen people try to use this one more often than the last one but give both a try if you’re looking for real estate integration for your website in Ontario.
The installation instructions are included in the link. This plugin, like my last one, will require a template to be made that displays the properties using the custom fields they are saved in. Other than that and for setting your username and password it should be good to go out of the box and take the hard part out of integrating your site with the TREB database.