In the ATM 49 package there should be part 1 and part 2 wrapped by a sheet with instructions, follow the steps and You should be good to go.
IMHO, the safest route is to use distilled water, so that You will always have same results. Tap water is hit or miss, even when filtered.
Studional was available back in the old Agfa times.. Now, You can rely on ADOLUX ADX A+B - for me it works the same, if not better.
Good luck and have fun in the darkroom!
ATM 49 gives very retro look