There's nothing like dropping a show right when it's concluding. It makes you question the point of watching the show at all. The River was only eight episodes, but the way that it moved through ideas and plot twists made it feel like a full-length season. That doesn't mean it was a good television show - far from it, actually, because it generally tended to rush everything until it blended into a mush of bits and pieces that didn't fit together.
That's also how The River concludes with its two final episodes. "The Experiment" picks up the search for Emmet at an abandoned research facility in the middle of the Boiuna - an awkward place for such a thing, admittedly, but one the show shrugs away because they were doing some unethical research and that's supposed to make sense. Emmet must be here, say the group, and so they begin to explore, finding zombies who have been turned by a virus created in the facility.
Do zombies fit with The River's MO/ No, but that doesn't seem to matter. And when it's revealed that a woman who Kurt was in love with was working at the facility, it makes little sense to us - Kurt has been a mysterious figure throughout the show, and he's rarely had anything divulged about him. This added fact just continues the theme where The River presents something and doesn't follow through.
But we do find Emmet - the main premise of The River has been fulfilled! Yet in "Row, Row, Row Your Boat", questions remain unanswered. The magic that Emmet set out to find in the Boiuna appears to have been found, but it is also never explained; what Emmet was doing, why he risked so many lives (including those looking for him) isn't given a resolution.
But guess what! There is a storyline about exorcisms thrown in for this last episode, encompassing the death and rebirth of Lincoln. It's a way to have Lincoln deal with his dad issues, the things that have plagued him throughout this trip to the Amazon, and I guess it's meant as the only kind of resolution we're going to get from a show that shies away from doing any kind of hard work expositionally.
As for a conclusion, there really isn't one. It feels The River doesn't end, and that could be because the writers left it open for the show to continue if it became popular. But The River's winding narrative wore thin far too fast, and the ridiculous, snap decisions of the characters in these last two episodes ("It's Emmet, I know it!" turns to "He's dead. I know it!" in minutes flat) are the reasons the journey along The River has come to an end.