Building an interactive website for our Accounting

Want to make a unique website and maybe an app that canallow client's to connect and login in for their information. We want a way to interact with clients online and have our client send files virtually to make life easier for everybody. Also need a way to pay for our service though the website and maybe a mobile app. Also wanted to have a section where we can put videos about the accounting stuff. Want to have the best customer experience and have ux/ui designs.