As for the pH, your fish are not likely to be wild caught. Captive raised fish are typically well adapted to the local pH. AS FF said, stable pH is most important.
Angelfish are hardy fish, but not hardy enough to cycle a tank with them. Since you have enough fish in the tank to cause an ammonia spike, you only have three otpions. First, lots and lots of water changes to keep the ammonia down. A python realy helps with this. Second, get some colonized biomedia from another FW
tank to jump start the bacterial growth and limit the duration and peaks of the ammonia and nitrite spikes. Biospira could be tried as a substitute, but is more variable in effect. Third, take some or all of the fish back till the tank is cycled and settles down. If you take all the fish back, you will need an ammonia source to add to the tank to grow bacteria. If you take only some back, you need a really small fish load to establish a biofilter with fish safely.
Read up in the articles section, and you can see how I have used fish safely at:
Some other things you can do, test your tap water for ammonia with a quality liquid reagent test kit. If positive, you have chloramines in your municipal supply, and need to always use dechlorinator. Also, test your tap for nitrates. If more than zero, you won't know your cycle is done till that level definitely increases. Since you have 5 ppm
of nitrate in your tank this early, I would assume it came from the tap and you will need to see the nitrate increase to 10 or 20 (with ammonia and nitrite zero) to be certain the cycle is done.