I use Windows 7 and LR 5.2, so it should work?
Yes, the Juicebox Lightroom Plugin should install and run fine on Lightroom 4 or later.
Also when I use the plugin manager of LR and I search for the noticed folder Than I get a failure notice, that LR could not succeed
The Juicebox Lightroom Plugin is not technically a Lightroom 'Plug-in' (and it cannot be installed by Lightroom's 'Plug-in Manager'). It is actually a Lightroom 'Web Engine' and, once installed, shows up as a 'Layout Style' option in the 'Web' module.
Installation instructions can be found on the support page but below are some additional details which should help you to successfully install the web engine.
You should be able to install the Juicebox Lightroom Plugin as follows:
(1) Extract the Juicebox-Pro v1.5.1 zip file and you'll find the Juicebox Lightroom Plugin in this location:
juicebox_pro_1.5.1/adobe-lightroom-plugin/juicebox_pro.lrwebengine
(2) On a Windows PC, juicebox_pro.lrwebengine looks like a regular folder but you should be able to install the web engine by dragging and dropping the juicebox_pro.lrwebengine folder directly onto your Lightroom desktop shortcut (and a small pop-up dialog box should ask you if you want to install it).
On a Mac, juicebox_pro.lrwebengine is seen as a special package and you should be able to install the web engine by double-clicking the juicebox_pro.lrwebengine package. (Please note that this double-click method does not work on a Windows PC.)
(3) If the auto-install methods from #2 above do not work, then you can install the web engine manually by copying and pasting the complete juicebox_pro.lrwebengine folder/package (not just its contents) into the following location:
Mac OS X - Users/Username/Library/Application Support/Adobe/Lightroom/Web Galleries/
Windows Vista, 7, 8, 8.1 & 10 - C:\Users\Username\AppData\Roaming\Adobe\Lightroom\Web Galleries\
On a Windows PC, you might need to show hidden files to navigate to this location in Windows File Explorer.
If you cannot find Lightroom's 'Web Galleries' folder on your computer, then please try the following:
Open Lightroom.
Go to 'Edit -> Preferences...' (from the drop-down menu at the top).
Select the 'Presets' tab.
Click the 'Show Lightroom Presets Folder...' button.
Navigate inside the 'Lightroom' folder in the file explorer window that pops up.
Now navigate inside the 'Web Galleries' folder. (If the 'Web Galleries' folder does not already exist inside the 'Lightroom' folder, then you'll need to create it manually.)
Now, paste the juicebox_pro.lrwebengine folder/package directly inside the 'Web Galleries' folder (overwriting any existing juicebox_pro.lrwebengine folder/package).
Before attempting the manual method, try deleting any existing juicebox_pro.lrwebengine folder/package from the 'Web Galleries' folder and re-try the auto-install method for your platform (Windows PC or Mac).
(I realise that you use a Windows PC but I've included some Mac details above, too, as it may help other users facing a similar problem.)
I hope this helps.