I would loosen the rootball. If the roots were circling as much as you described, I would also make vertical cuts about every 1 to 2 inches apart to help with loosening it. If you do not loosen it, it will eventually die in a year or so.

Do expect some wilting even without this root problem. On their first year, hydrangeas suffer from wilting when the temperatures get hot and when the hot drying winds affect them. This problem occurs when the leaves loose moisture faster then the roots can absorb moisture. However hydrangeas usually recover on their own a few hours after nightfall, when the imbalance between moisture lost and moisture absorbed is corrected.

The key is to monitor them during their first summer and to check the soil when you see wilting. If the soil is moist, you can leave them alone and they will recover. If a finger inserted to a depth of 4" (not counting the mulch) feels almost dry or dry, immediately give them about 1/2 gallon of water. Adding and maintaining 3-4" of mulch will lengthen the times between watering and help the water not evaporate quickly.

If they remain wilted all the time and the soil feels moist then that indicates another problem: root rot due to too much water or soil that does not drain the water fast enough.

Hint: do not fertilize a stressed plant. Normally, there is no need to do that it if the potting soil mix came with those round fertilizer pellets.

Hydrangeas do not have to be fed often like roses and only nibble at their food source. Just give them some liquid seaweed or liquid fish with your waterings; they will complement the fertilizer pellets. These are weak fertilizers and should be fine to use on stressed plants.

Hint: if the location is windy, this could cause the plant to loose moisture quickly. You can consider transplanting it or blocking the wind with something (a plant or an object). The night before a wind advisory is issued, consider watering.