Implement submitting form from the site

There is a site www.hybridwork.ru/, implemented on CMS Webflow, through it now sent a form. The site we transfer to external hosting, respectively, you need to prepare an external form handler and connect it. An important condition - when refiling the contents of the site on ftp, the work of the form should not suffer.

In the proposal, please include examples of similar works, estimates of the time and cost.

Thank you.