Max, it might be a good idea to test the pH of your soil in that bed. Citrus need an acidic soil to be able to take up the proper nutrients. You can get a pH test kit at any nursery or garden center, or get the soil tested at the County Extension service.
Also if you are watering with well water, it would be a very good idea to test the pH of your water as well. Even if the soil pH is ok, if you are watering with alkaline water (my well water is pH 8.2, way too high!) it will still affect the ability of your tree to use nutrients.
All that aside, I'm very surprised that you have been able to buy a citrus tree at all these days. The whole state is pretty well infected with Citrus Greening disease. That could be what is causing the curling leaves and mottled appearance as well. You can keep the tree alive for a few years if it is infected but once the disease really gets hold of it, you will not get any fruit worth eating.
Master Gardeners here in Sarasota County have been instructed to advise people not to plant any new citrus of any kind until some sort of solution to Citrus Greening shows up. Don't be fooled by con artists advertizing any "Citrus Greening cure". I've been a MG here for 12 years and it breaks my heart to tell people their trees probably have this disease. Some may survive, but most will die.
If you bought the plant from a reputable nursery or store, you should be able to return it and get your money back, and that's what I'd advise you to do.