How to implement automatic download of updates (Unity)?

Question

Unity

Good afternoon! I really want to implement automatic downloading of updates from some remote server in my application, but I have not yet encountered tasks of this kind.
What I need:
1) Implement automatic download of updates from a remote server when the game starts and the Internet is available;
2) The update will consist of several dozen ScriptableObjects;
What I understand:
1) To do this, you need to deal with assetBundles;
2) Most likely, pushing pure SO into the bundle will not work. First it will need to be serialized (correct if wrong);
2) To do this, you need to rent a small server (?)
What is my problem:
1) This is my first time working with a network;
2) I do not fully understand the principle of working with assetBundles;
3) The budget is very limited. I don't know how much it costs to rent a server.
Please share your experience, attach links to useful articles.
If I misunderstand something, please direct me.
Thanks to everyone who will respond.