Hello, how are you?
I've read your description and I have very similar sample.
Please check my effort.
https://www.freelancer.com/projects/software-architecture/Java-Spring-Architect/?w=f
This project is built using Angular 7, SpringBoot 2.x, MongoDB.
And I used AWS S3 bucket and EC2, ECS, SES etc and used MongoAtlas for MongoDB hosting.
If you want, I can show you well structured code snippet right now.
For me, most important is high quality and speed.
I will give you wonderful guide as you want.
Let us discuss in detail via chat.
Best regards, Peng.