web application based on R language

I want to develop a website based on R language. It can be hosted on DigitalOcean in which we need to install R language and the required packages.

The website should be interactive enough for users to be able to generate plots and to be able to download them. The functions that will be used for generating plots or processing specific files to generate other output files, I will implement it by myself with the help of the developer.

There will be “applications” section that we will implement different applications to be inside and each application will have different functions, so users can use them.

We will need to create a swap file to avoid any Ram problems.

There will be subscriptions plans for users to subscribe

There will be an admin control panel, and the admin can:
- Verify users
- Give permission to users for which app they can use.
- Assign a dedicated space (gigabytes) for each user, so there will be a limit for each user regarding the amount of space to be used and RAM as well.

Each user will have a folder on the server in which the user can upload files or create subfolders inside or download files from the server to own computer. When the user will need to use an application, the user will need to upload the files first in his folder or sub folders and then open them through the applications.

Phase I of the project will be as follows:
1- Installing the required R packages
2- Implementing the functions and use them through the web interface and users can upload and download files from the server to computer.
3- Once point 1 and 2 would be completed, we can start developing the rest of the functions and features.

Please, when you are going to bid, let me know what framework you are going to use and what if any limitations we may face. Also, it should not be through using Shiny App.

Thanks