Custom website with workflow / database / admin / mobile friendly

I need a website creating for a bespoke website. The site will guide users through the process of managing projects and will therefore use workflow throughout each stage. Different documents will need to be completed before the site will allow the user to progress to the next stage. I need an admin area creating and also each user / project will need its own secure area too. The database and any files need to be stored in the cloud ideally in Amazon or Azure. This is to be compliant with enterprise data storage guidelines. The site also needs to be mobile friendly so projects can be updated on the go via mobile. The workflow is complex and also confidential so I will need to make sure we have a good relationship before sending any further documentation. I do have some ideas on how I'd like the site to look and feel but I'm happy to listen to any other thoughts as I'm not a designer myself.