Keep the Magnifica on that rock. If you remove him, you will cause unwanted stress and trauma.
Normally you would start with 250mg. Your anemone is in critical condition, so start with 500mg which is double the recommended starting dose.
You can either let the pill dissolve in front of powerhead by rubbing it with your finger. Or you can crush it up on a plate with a spoon or something flat. The finer you get it crushed the better. If these are "film coated" they may not dissolve well by using your finger in front of the powerhead. I would crush it if I were you.
To answer your question about the antibiotic you ordered...yes, it will be good to treat the anemone if it's Cipro. Doesn't matter if it is generic.
Again, divide your treatment tank in half. Put heater and powerhead on one side, and anemone on the other side. Make sure you have egg-crate divider In-between to protect the anemone incase he starts moving around in the tank.
Put a good light on him with light to moderate flow. Make sure you don't have too much flow while he is sick because they get weak and can't hold themselves up or keep attached to the rock or bottom of tank.
Do not try to feed him right now.
Again, dose 500mg about 8pm every evening "after" you do a 50% water change.
If the water is cloudy, do a 80-90% water change. While changing the water, siphon out any junk floating in the water or on bottom of tank. Be extremely careful not to suck up the NEM in the siphon tube. Don't even siphon around him. One mistake like that at this point can cost you his life.
Please read OrionN's protocol at the top of this page as suggested. All the information is there.
Good luck and keep posting pics. Use the IMG code (bottom link) not the direct links.