The command in main.sh that fails is this one:
/opt/oracle/product/12.1.0/dbhome_1/bin/dbca -silent -CreateDatabase -templateName my_oblicore.dbt -gdbName oblicore -sysPassword oracle -systemPassword manager -characterSet AL32UTF8 -nationalCharacterSet UTF8 -variables OBLICORE_ROOT=/opt/oracle/
[FATAL] [DBT-06005] 'FRA Location' contains invalid characters.
ACTION: Choose a 'FRA Location' containing only alphanumeric characters and a few additional characters that are allowed for your platform.
There is a bug in Oracle 184.108.40.206.0 that causes this. Either download the patch, or remove the -silent flag from the command. https://www.oracle.com/webfolder/community/oracle_database/4083641.html