I just tried the new ODBC driver for macOS & Excel 2019. Configuration & connection to database works with the iODBC Administrator64 tool (after some tweaking with the directories for openssl and iodbc libraries). When trying to connect via Excel I get that well-known IM003 error that the database driver cannot be loaded. Same happens initially for the mySQL ODBC driver. Assumed reason is that Excel is sandboxed and does not allow loading of executable code from arbitrary lcocations (I assume locations like /usr/local/opt/... used by the .dylib to load dynamic libraries), see reason & workaround at https://github.com/openlink/iODBC/issues/29 at posting of `smalinin commented on 6 Mar 2018'. The workaround using the mySQL OBDC driver binaries & file locations works also for accessing a MariaDB. The workaround does not work for the MariaDB ODBC driver binaries since it tries to link to libraries not allowed by the Excel sandbox.