What brand/type product do I need??

Tap water is fine

brand like "biobizz" or "bio canna" are real efficient and simple to start with.

Bio Vega and Bio Flores made by Bio Canna are superb, just one bottle for growing and one for flowering - super simple! Both are complete nutrients, meaning nothing else to buy or mix. Have used them for years and the results are excellent, but half strength is usually plenty, especially when still small. Both are also very concentrated, meaning a bottle lasts ages.

Bottled water is probably not the best, imho... the PH is too alkaline in a lot of them. You need to invest in two things: a simple nutrient package (most will have nutes you give in the vegetative state and then ones you give when the plant is in flower)... but equally as important is to invest in a PH pen like right NOW - I like Apera because it's just as good as, if not better, than Blue Lab and slightly less expensive... but maintaining a PH level between 6.0 and 6.5 is going to be crucial to avoid problems down the line. Good luck!

get some biotabs and bury 2 in each 5-10l pot and do only an only water organic grow. your bud quality will be better and its gonna be a very easy ride.

Something simple, something that covers ruderails (micro nutrients) A dual part feed. So a grow, bloom µ. You give all 3 together based on ratios of what stage of growth you are in. Either something from GEH or Advanced Nutrients are cheap and widely used and great for beginners. I have dual feed from both. I like adv nutrients best. Jungle juice trio is only 24$ for all 3 1L bottles. And you get a Grow, Bloom and 1 of the best micros on the market. Jungle juice trio. https://www.led-grower.eu/advanced-nutrients/ You can get these WW at any grow store. Good luck.