2
Gonna need more info:
1. which version of xoops?
2. which php/MySQL versions are you running?
3. which version of xcgal?
4. does the "anonymous" group exist?
It sounds more like an error with your XOOPS environment or database (i.e. no or incorrectly defined "anonymous" group) than a module error.
Can you try again but with php debugging turned on?