Encore has a website with information about care for their plants. It is listed below.

Encore does not rate any of their plants for Zone 6; Zone 7 yes, Zone 6 no. I would be very careful with the plants and go back and see if the nursery gives you a guarantee on these plants.

Yours may do just fine, but there is little data from people who grew them in Zone 6. Your nursery may be the experts on this.

Here are some factors that you must consider to protect azaleas in the winter are:

Winter Wind & Sun: Azaleas may be harmed in winter by drying winds and bright sun; protect their shallow roots with a mulch of oak leaves or pine needles and their foliage with a loose blanket of evergreen boughs or specially built screens. Such screens must provide shade without capturing heat. A burlap screen will protect a plant while a black or clear plastic bag will cook a plant. Keep the mulch away from the trunk of the plant. This avoids bark split, fungus and rodent damage.

Antitranspirants: Chemical antitranspirants effectively cover the stomata, the pores through which the leaves loose moisture. However they must be designed to naturally degrade so they don't interfere with the normal operation of the stomata during the growing season. This usually means the antitranspirants need to be applied at least twice during the winter, but not too close to the growing season.

Dormancy: To insure that a plant has the ability to make it through the winter, it must be dormant. Dormancy is a normal process in which the plant goes into a rest state during the winter. Dormancy is caused by a number of things including short days, low temperatures and drought. Several things can break or prevent dormancy.

* Too much nitrogen fertilizer after mid summer will keep a plant in a growth state when it should be going into dormancy.
* Warm weather spells during the winter can break dormancy in a plant that has gone dormant.
* A warm fall followed by a sudden winter, can expose a plant to the cold before it has gone dormant.
* Too much light such as being planted under a spot light that is kept on all night.

Here is a link that might be useful: Taking Care of Encore Azaleas

Bischinha,
Arbor Day zone is what is posted on Encore's website, and even though I am in zone 6, I am in Arbor Day zone 7.
I bought an Encore azela also, and it is doing fine.
It does have protection from wind and I mulched it in for the winter.
Just see what happens. It will probably be OK.
They are beautiful aren't they?
I love the fact that it is still blooming and it is so cold here.
GOod Luck! You'll know in the spring!