Appart from the lenghty download from the Oracle public release Internet repository, my installation notes on the links above present some more powerful considerations that the graphical Package Manager cannot offer, so check it out!
NOTE
NOTEThe public release Internet address is https://pkg.oracle.com/solarisstudio/release but you'll only be able to access if you first register at http://pkg-register.oracle.com/ and later generate a PKCS12(1openssl) a.k.a. a PFX file to install on your browser.
After launching Solaris / Developer Studio for the very first time, it may be convenient to adjust the default project folder much the same as its done for NetBeans. Instead of looking for the projectui.propeties file at ~/.netbeans, do so at ~/.solstudio or ~/.oracledevstudio.