Can someone help me.
I downloaded all the files, but I couldn't figure out where to start.
We will try to help you ...
Have you ever used arduino ??
If not, you are leaving far too far and you have things to study before embarking on this project.
If yes, what is it that bothers you? The main file is called "MrAqua.ino"; it's him you have to load.
You couldn't figure out how to set the nextion screen.
IAqua has not been written for this screen at all, you have the list of materials on the Github.
I have alarms, mraqua, screens, touch files, but I could not find information about where they are used.
As said above, Mraqua.ino is the master file of the project.
You must load it in the arduino IDE.
All the information you need is in the whole thread. Yes, 140 pages to read are a big journey
but you can't do this project IMHO without the reading of the thread.