This appears to be related to incomplete task ODBC-201
I've attempted an installation with the package downloaded from https://dlm.mariadb.com/1936452/connectors/odbc/connector-odbc-3.1.15/mariadb-connector-odbc-3.1.15-osx-x86_64.pkg
It appears the libmariadb dependency is missing. This according to tool:
The message as relayed by Excel is:
I thought it must be a path problem. I can't find that file on my disk. I expanded the .pkg file and its Payload. That file is not in this package.
The release notes say Connector/ODBC is "based on Connector/C"; not that it depends on it. Still, I attempted to download the Connector/C for macOS, in case I was supposed to get it separately. A package for macOS doesn't exist.
I am still digging into this issue on my setup. However, I think this is a bug: the download provided doesn't have any chance of working out of the box.