Looking at Oracle 18c
After getting the database code trees installed I went on to the dbca creation
I saw there was a log directory for dbca creations
/u01/app/oracle/cfgtoollogs/dbca
The logs are listed in groups of (2)
starting with trace and silent
many failed attempts, but this is a good place to start to get the problems solved.
Currently we have a situation that the create failed due to ASM checks
Not sure why this is occurring as the ASM disks are up and available