@cole: thanks for the guidance as usual.
I still believe this issue lies with QuickStart VM setup, especially after reading this RS Community post.
In the post, @josh mentioned that Oracle professional driver is actually present in /opt/rstudio-drivers/oracle/bin/lib /liboracleodbc_sb64.so.
In our case, the folder /opt/rstudio-drivers/oracle/bin/lib doesn't event exist to begin with, hence liboracleodbc_sb64.so is not available for use, even though Oracle shared libraries (from instantclient install) are.