Think of Z2 and Z5 as interchangeable and completely identical with the proviso that Z5 has mild swirl hiding ability and Z2 is more optically clear so won't hide any swirls if you have them but may appear more glossy than Z5. That's it. You probably can just use Z2 if you don't have swirls.
Both are used like your UPP or SG. Apply, wait to dry, buff off, then let cure for 24 hours before another layer. Exact same thing as your UPP or SG. Only that you need to use apply Z1 immediately before you apply your first layer of Z5 or Z2. After first layer, you can apply exclusively Z2 or Z5 daily, alternate layers of Z2 and Z5 each day, etc. whatever you want as they are basically the same. Just top with Z2 as the last layer since it is supposed to be the best looking.
If you have ZFX, don't have to wait 24 hours for curing as it is cured by the time you buff off so can apply next layer immediately up to 3 layers/day.
Need to use another application of Z1 before Z2 or Z5 after every 6 layers of Z2 or Z5.