It's hard to say precisely without seeing the location :-) Some areas that do not receive direct sunlight still offer very bright light and that could be fine. And dappled or filtered shade for most of the day is usually fine as well. But heavy shade cast by an overhead structure or large trees may be just too dark to offset only that one hour of sunlight and if that's the case, your ES may suffer from lack of flowering or not much flowering. Only you can judge for sure!

Posting a photo of the location could help to clarify.

Oh yea I forgot to say, I live in northern NJ in zone 7a. But I already planted that hydrangea there.. There really isn't any other spot to plant it so theres no choice. Alright well here are two pics of that location. The area with the bare soil with the trowel on it(the hydrangea wasn't planted yet at that time I took this pic). And yes the sun is blocked by my house and 3 eastern redcedar trees. Oh, and I would also like to say that I have some hydrangeas planted in an area that gets 3 hours morning sun with complete afternoon shade but the blooms still become fried and turns brown. So that is why I thought even 3 hours of direct morning sun is still too much for endless summers.

My Endless Summer gets a couple hours of afternoon sun from the west. It is frying and will be moved asap.

You can get a fungus called gray mold that makes the blooms feel papery and turn brown. And lack of water could make the shrubs start browning blooms early. I get some browning due to temps now and that includes some shrubs that are in the shade. Depending on cost/etc, you can try to add afternoon shade with the use of 35% shade cloth and see if that helps too.