If the question is how to integrate the reservation app to your Webflow page, then I think the place to start checking, is if there is some reservation app or third party services on the web, that will let you embed some snippet code to the page, and let you insert the reservation app to your page that way.
If you need something standalone, i.e. you are installing your own reservation system software on your own server, then you may need to export your files from Webflow first and edit those files with your developer outside of Webflow.
I cannot comment about Wordpress, since we support only Webflow, but there may be multiple ways to integrate a system like this. My suggestion is to get a developer to help you to understand what choices there are and how to get those implemented.
I hope this helps. If not, please let me know – I’m happy to assist further!
As @cyberdave says above its best to find the right third party booking app that suites your clients needs that also provide the ability to embed onto the site you are developing. A couple of options I would recommend are Rezdy or Checkfront
Both of those offer a number of embed options. I went with Rezdy and can refer you if you would like? They gave me the ability to integrate a booking system for snowboard camps at www.ninjacademy.co.uk
The beauty of this approach was that I simply set up a modal in Webflow that calls the booking application and it all works a charm.