ODBC Data Source administrator requires a privileged postgres account

I'm trying to set up an ODBC datasource to a postgres DB on windows. I'm using ODBC Data Source Administrator (64-bit) with version 13.0 of PostgreSQL Unicode(x64) driver.

I've set username to postgres with the appropriate password. Clicking on the test button tells me the connection is ok. However, the postgres account is the top-level, master account that gives full access to the postgres database server. How can I set up the ODBC datasource to use one of my read-only accounts that have access to just the required data/views only? The error message for any of the accounts I want to use is FATAL: password authentication failed for user 'myuser'

(not sure if this is relevant but... Database is called myDb, SSL mode is disabled, server is localhost, port is 5432)

Update in response to comments - the postgres log entry also says authentication failed. Resetting the account makes no difference (nor does creating a new account just for testing). The database config file postgresql.conf indicates that password_encryption = md5. If memory serves me correctly I had to switch to md5 to allow .net applications to connect.