Strictly speaking, you should do another water change to get it below 0.25, but as you posted this last evening, it is a bit to late to say that now
[I usually turn my laptop off at 7.45]
The aim is to do a water change as often and as big as necessary to stop the ammonia (and later nitrite) ever getting as high as 0.25. If it is at 0.25 after a water change, it will only go over that before you test again. With a 64 litre tank, it isn't that hard to do big water changes. I have a 125, a 50 and a 30 litre tanks, so I know how much effort a 64 litre would be
Ammonia burns fish's skin and gills - and that makes it harder for them to absorb oxygen from the water. Nitrite binds to the red blood cells stopping them carrying oxygen round the body, the same way that carbon monoxide kills us.
Your pH is at a level where any ammonia in the water will be quite toxic, so those water changes are more important. Ammonia and ammonium are in an equilibrium. The higher the pH, the more that is in the ammonia form. At lower pH, more is in the less toxic ammonium form. Your pH isn't as bad as the 8 that some regions have, but it is still a bit too high for having ammonia in the water.
With soft water, it is possible you have a low KH (carbonate hardness). You can buy testers for that but it would be cheaper if you asked a fish shop to test a sample of your tap water for KH. The filter bacteria need a source of inorganic carbon - ie carbonate - in the water in order to multiply quickly. If your KH is low, that could be slowing them down. If you do get it tested and find that it is below 5, the best thing to do would be to add some coral or limestone to the tank - a piece of coral, a bag of crushed coral, a limestone rock - as they would slowly dissolve putting carbonate in the water. With fish in the tank, the method for raising carbonate in a fishless cycle can't be used.