This is a nice project, you must've worked hard here.
What was used to create it? How would one learn how to create this? How much was coded/created from scratch?
I used Yii2 php framework, to create it.
You should read Yii2/SQL/API documentations, some books about php-programming, OOP, MVC, CSS/HTML, JavaScript/jQuery, Bootstrap and after that you can try to do it
All the project was coded/created from scratch, using the functionality that Yii2 gives to me.
PS: if someone likes project and find it useful, I don't mind if you'll donate a little to the wallets at the bottom of the site. So I can pay my hosting company and keep it online