What in the world is it?
If that was suppost to be some kind of pergala, the boards are way to close together and will be near imposible to sand and paint properly, there also way undersized.
If there pressure treated paints not going to stay stuck to them. It should have been allowed to dry out then soild stained not painted.
Any job is 90% prep work for good results. There is no magic wand or "special coating" to cover up peeling up paint.