You have to actually understand it. You're asking very basic questions and don't even have the proper equipment to grow. Then you are wondering why you are having issues.
You don't have a working pH meter, but have a jug of water labelled "6.2 pH". You don't have an EC/ppm meter. You are asking what to feed it. You are taking the plant out of the tent and bringing it outside.
These are the basic things I'm talking about. I understand it's overwhelming at first for sure, but a basic understanding is required to get a plant to harvest.