Your azalea needed to be kept moist, but with good drainage. Leaving it in the plastic liner may have been a fatal mistake, you'll know soon enough if the roots suffered to much to recover.

Most of us don't find them the easiest of indoor plants - my own house has humidity much too low to keep them happy with a heat pump and the constantly circulating air.

Attached is the page the Azalea Society links for indoor culture, see how close you can come to meeting the requirements.

Here is a link that might be useful: Azaleas indoors

Florist potted azaleas are not easy to keep permanently as houseplants. They are hybrids that aren't hardy in much of the country outside, grown for their ease of bloom in greenhouses for the gift/florist trade and they are grown in almost pure peat most of the time.

A cup to a cup and a half of water may have been far too little if you had proper drainage. One wants to thoroughly soak plants less often rather than dribbling small amounts on them often. If it gets bone dry the potting mix shrinks and water runs out the sides instead of soaking the rootball. Dunking in a bucket can get them fully hydrated again but if they go bone dry more than once or twice they are usually goners.

One always should remove any decorative paper or wrap or drain any pots used to dress up grower pots.