Look at README.md

This is a fork of Cyrus-Sasl 
It builds into the main daemon (not a library plugin) the ability to use 'sql' as a mechanism.
Currently, it has hard coded a query that will work on most modern postfixadmin 
based virtual email systems.
If you started out with dovecot and postfixadmin, and want to move cyrus IMAPD, 
you need a SASL that can work with a postfixadmin database. 
SASL did not appear to have any support for Argon2 password hashes. 
This fork requires additional libaries not required by Cyrus SASL. 
You will need mariadb or mysql development libraries, and the Argon2 development libraries. 
Security Problem: This version gets the database login informaion from a configuration file.
You must keep that file secure or adopt an encryption strategy. 
The SQL configuration is as documented on CYRUS SASL web pages.
I discovered that 'sql' was not available as a mechanism when building the original code.
Additionally, there was no Argon2 support built in. 
As labeled I started with Cyrus-SASL-2.2.28 release version.
I had to make some minor changes to get some original sources to work:
There is a macro that is common in other Cyrus projects, assertionfailed(), that was
breaking as undefined (Ubuntu 22.04 LTS). 
Other than that, everything different from Cyrus is an addition. SQL is added as
mechanims, with initialization and verification call backs in the new files added.
Must link with -largon2 and -lmysql or -lmariadb