You are developing a new mobile application and are considering storing user preferences in AWS. 2w This would provide a more uniform cross-device experience to...

You are developing a new mobile application and are considering storing user preferences in AWS.
2w This would provide a more uniform cross-device experience to users using multiple mobile devices to access the application. The preference data for each user is estimated to be 50KB in size Additionally 5 million customers are expected to use the application on a regular basis.
The solution needs to be cost-effective, highly available, scalable and secure, how would you design a solution to meet the above requirements?