Hey Max
If you wish to use AJAX then the page the search form is on must have a similar layout to the search results page.
So, try disabling ajax, then check the page the widget is embedded, and the page with the search results, and they both have this container et_pb_portfolio_items
and also that on the search results page this container does in fact have the correct results?
The url that is called is exactly the same as the URL for non ajax results – it basically loads the next results page like normal, but via ajax, and finds your selector on this page (ie .et_pb_portfolio_items) then copies the results over in to the page you are currently on.
In terms of going back to the drawing board and customising the free version to use ajax, that is up to you, but this is exactly the process I did and you have paid for this plugin so I would of course not recommend it for several reasons.
I won’t be able to help you set this up unfortunately thats out of the scope of support – but setting up this plugin to work as intended is!
Thanks