Web portal - for machines

I’m looking to create a web portal for construction machines and plant.
It’ll be a search engine to find machinery and plant for sale in the UK. I would like users to be able to sign up and pay per listing to post their machines for sale (essentially autotrader for machines and plant), and a separate subscription model for companies who will have multiple listings. There is an excellent theme which I believe will cover this via this link: https://motors.stylemixthemes.com/equipment/
There will need to be some amendments made for this theme, such as how the pages look and the categories of machines. There are more details too but if anyone can help me get the website up and running that would be a great start. Please, no generic responses. I’d like a specific reply stating how you’d to do this project.