Trouble connecting to slack

Issue Summary

I am having trouble Integrating Redash to Slack. I am trying to do this through the Redash app on Slack. I enter our redash url and API key, but am always given back the folliwng message:

Failed validating credentials please make sure you used the correct API key & your Redash instance is accessible. If you want to start again just tell me “start setup”.

I suspect that the cause is because we have Basic Auth. set up on our redash page. I did some search and allowed Slack’s IP address through the nginx settings, but no luck

Technical details:

Redash version 5.0.1+b4851
Using Slack from Firefox browser 72.0.1 (64-bit) on Mac OS Catalina (10.15.2)