I use Poe and got access to Claude 100k as soon as it was released. I think it's a better deal than paying OpenAI for sure, since you have access to GPT-4, Claude+, and others. They also have community bots, etc.
I'm a graduate student doing AI research in a US University. And I applied pretty early (Last year December I think) , those might be two factors that got me access to Claude.
I think getting access to Claude through slack is much easier and I recently got it by just downloading it as a Slack App
Claude has a free slack client that I briefly was able to access by creating a new slack workspace and adding it there. But as of yesterday it wasn't working for me