Correct system architecture with tags?

Question

PHP

Good afternoon.
Please tell me the option how to organize the architecture of the application.
The system will be written in php, mysql database.
Briefly what is the system:
There will be many users in the system, each user can create messages in which he can upload up to 10 files. There can be as many of these messages as you like, and accordingly there can be a lot of files (both small and large). Users can add tags to messages, as well as to files, tags are created by the user himself. Users can create as many tags as they want and add as many tags as they want to each file/message.
The user can search by tags.
Actually I'm asking for advice:
1. How to properly organize file storage? Suppose each user has his own folder where his downloaded files are stored, but there can be hundreds of thousands of these files, and then, as I understand it, the file system itself may have problems.
2. How to properly organize a database with tags and search by tags? How to optimize as much as possible so that there is the least load on the database?
If I may have made inaccuracies somewhere in the description - I ask you to forgive me in advance.

Answer 1

normal form