What PHP version are you using?

8.4.3 via Laravel Herd

What if you don't use the -W flag? (We don't instruct to do that)

Oh how strange! It wasn't workin without the -W at first which is why I tried adding it but now it's working

Thank you for your help Dennis!

Excellent!

Oh wait no, so sorry to be a pain it's not working still :( I'd accidentally installed it in a project, global installation with or without -W still isn't working for me

It seems you have a conflicting composer package globally installed, which requires symfony/yaml:6.4.8 but ploi/cli requires ^7.2.

You could check where the dependcy comes from with:

composer global depends symfony/yaml

Or check the global composer file in ~/.composer/composer.json.