I recently downloaded Movie Studio 13 32-bit Trial for Windows. It works perfectly on my 32-bit Windows 7 machine. When I click on BUY NOW, it takes me to a web-page where I can purchase Version 14 which is 64-bit and WILL NOT work on my computer (I've tried it). I am NOT going to upgrade to 64-bit windows. What do I do?
MAGIX dropped 32-bit versions of their VEGAS and Movie Studio releases. If the OP is talking about Sony Movie Studio 13 32-bit (not Platinum version), it is currently still archived here. (13 Plat. here) Those are the last Sony/SCS builds.
Unfortunately, to buy a license for those 32-bit versions you need to do what is suggested by FayFen above (and previously by Cornicohere and currently by Nick here.)