Leopard systems (Macintosh OS 10.5.8) automatically have 64-bit Java installed, but in order to run SoftChalk Create the 32-bit version is required as well.
There are two solutions:
1) Upgrade your operating system to either Snow Leopard (10.6.8) or Lion (10.7). These operating systems automatically have both versions of Java.
2) OR You could try downloading and installing the Java in the 32-bit format for your Macintosh OS 10.5.8 system. The minimum version required is JRE 1.6.0_24. This is a fairly technical process, so it may require the help of someone from the IT department at your institution for this solution.