Adding a solution specific to my situation. Installed MySQL by way of MAMP (cause it's 'easy'). Needed workbench specifically for the ERD generation. Workbench couldn't connect to local mysql installed by mamp; other clients could connect.

MySQL installed by MAMP creates a root user using mysql_native_password plugin which is not supported anymore in MySQL 8.4.

Followed instructions here to change PWD storage for that same root user to sha2 cache:

https://php.watch/articles/fix-php-mysql-84-mysql_native_password-not-loaded

Relevant commands are:

1. Check that it is in fact native password problem:

   SELECT user, host, plugin from mysql.user WHERE plugin='mysql_native_password';

2. Change the user(s) to remove the need for native password plugin:

   ALTER USER 'USERNAME'@'HOST' IDENTIFIED WITH caching_sha2_password BY 'NEW_PASSWORD';