Error during 'composer require'

[jmconsulting]

When running composer require daveearley/daves-email-validation-tool

I get:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for daveearley/daves-email-validation-tool dev-master -> satisfiable by daveearley/daves-email-validation-tool[dev-master].
    - Can only install one of: daveearley/daves-email-validation-tool[v1.1.0, dev-master].
    - Installation request for daveearley/daves-email-validation-tool ^1.1 -> satisfiable by daveearley/daves-email-validation-tool[v1.1.0].

This is on MacOS Catalina, php 7.4.1. Have tried reinstalling, updating composer, php, etc.