Hello Tacokkat and welcome to the forum.
Did you not get some installation guidelines in an email?
Anyway
-- installation of the software and the samples library are separate activities,
-- it sounds like you have Registered the hardware,
-- and downloaded ST4 from your User Area,
-- you should see "SampleTank 4" and "SampleTank 4 CS" in your Uaer Area; the latter is the free one.
-- go down to the one named "SampleTank 4"; the big red button downloads the software
-- click on [Sounds Download} and you should see a drop-down list of files
-- download each one, keeping a check to make sure you do not miss any.
Now
-- install the ST4 software, standalone program and the plug-ins you want (and the included Custom Shop and Authorization Manager programs),
-- the installer will remind you about the sounds library files,
-- run the Authorization Manager and Register / authorize ST4 using the Serial Number from the "SampleTank 4" entry, NOT the "SampleTank 4 CS" one,
-- run the standalone ST4 program and in Settings / Sound Content, set the disk path to the location where you want the sounds library to be installed, close ST4,
-- my path is X:/IK Multimedia/SampleTank 4
-- for each of the downloaded sounds library files, extract the contents from the file to your Desktop, run the installer, select your main library path if needed.
Keep the downloaded Sounds Library files on a back-up disk so that if you need them again, you do not need to download them again.
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Also, click this:
https://www.ikmultimedia.com/faq/index.php?search=SampleTank%20installation and look at "Getting Started with the SampleTank 4 (Digital Download) Installation Process".