The title of the product page [Almost] says it all: "Ultra-realistic Images in the 5th Generation"... just have to replace "Ultra" with "Un" [as in UN-realistic]. ¯\_(ツ)_/¯ The app itself isn't necessarily bad, but it's an FX app that can also handle HDR images, rather than any soft of pure HDR software.
OK, why HDR?
Cameras by themselves or on their own capture or record the image that comes through the lens. Because more light will pass through the lens on a sunny day at the beach than inside your home or say in the woods, there has to be some sort of control limiting how much light gets through -- otherwise some photos will turn out all white, and others all black. So cameras vary their shutter speed, which means how long light will be allowed to pass through the lens for a single photo, and/or they vary the lens aperture, which means making the opening the light passes through bigger or smaller. While some phones have cameras controlled by software that can greatly even things out, generally speaking, automatic cameras will measure the scene's lighting and adjust things as needed, manual cameras will rely on you to make those settings, and fixed cameras will sort of just let you hope for the best.
If the sky or background is bright, and the subject in your photo isn't so well lit, the photo you get will depend on how the camera [or you, if the camera isn't auto] measured the scene's lightness. Usually it'll look at the center of where you pointed the camera, and the sky will be too light, the subject a bit too dark, but overall [hopefully] you'll be able to make out the subject in the photo. And usually if you've got a little experience under your belt using image editing software, you can *somewhat* make up for that, darkening the sky or background, and lightening up the subject. Problem is, you're limited by the amount of data that the camera captured in that photo, so you can make it better, but it's still not going to look just like what you saw when you took the picture.
With HDR you take one photo with the camera adjusted to take a great picture of the sky, knowing the subject will be way too dark. Then you take a 2nd photo with the camera set for your subject, again knowing the sky will be almost white. Now you could take the sky from one photo and paste it over the sky in the 2nd, and that works, but HDR makes it easier by combining the data from both photos into one image.
Normally that's done on a mid to high range camera by setting the camera to bracket exposures. What that means is the camera takes one photo normally, then adjusts itself to take one photo at a lighter setting, and another photo with everything set to be too dark. Originally the idea is that one of the 3 might turn out if the lighting was difficult, but it works fine for HDR. An HDR image has all of the data from each individual photo -- it's up to you and the software to decide just which data to display, and which data to just sort of ignore, making those parts that need to be lighter, lighter, and the same with the shadows and darker portions. Ideally you do that HDR merging part in your editing software so that all that data's available when you do whatever other processing the photo needs -- balancing out the light and dark parts does nothing to fix any other problems the image may have.
IMO that's best done in PhotoShop/Lightroom, just because of that, though HDR projects can work as a plug-in, getting you almost there. Otherwise, if you save an HDR image you have to worry about how to get all that data into your editing software to make use of it -- there are a couple of file formats you can use, but some data may be lost, &/or your image editing software might or might not work well with that format. HDR works best when you have your photos in a RAW format -- since your goal is max data, use the format [RAW] that contains the most data.
Now, that's all hum drum -- not at all exciting -- and just a lot of extra work for results that many people don't care about when it comes to their own snapshots. Franzis wants to sell a Lot of software, so they try to make HDR projects exciting, hoping that then you'll buy it. So they add all sorts of FX stuff hoping you'll go: "WOW!". That stuff has nothing to do with HDR, but it can mask problems so you don't have to edit, and they provide some editing tools so you can tweak your photos a bit. Rather than tell you that's what they're doing -- and that it's HDR irrelevant -- they include synthetic HDR, meaning you're using the app's FX, just skipping the HDR part.
As usual for their giveaways, during install you can copy the real setup file from the user temp folder, HDR projects 5 DE_EN_FR Setup.exe. That setup file adds yet more copies of Microsoft's C/C++ runtimes, which is why I install it in a VM, then copy the program's folder to my hard drive, running and activating it there. [Check the size of your C:\Windows\ WinSxS\ folder if you want to know why I object to more copies of the runtimes.] Of course doing it that way uninstall doesn't work, but I'm OK with that.