1) Generated Webhook URL looks like https://admin:firstname.lastname@example.org?chargebee_webhook_call=true
Actually part admin:hgd765tgfrjhfdhjfhhf87587tgfh@ is not needed, as credentials should be entered anyway on webhook settings page.
2) Plugin says " Copy the URL below and paste it in the "Return URL and
"Cancel URL" fields in Chargebee under "Settings > Hosted Page
Settings > Hosted Checkout Page". "
But on this settings page there is no term Return URL, but Redirect URL.
1} Actually you would need to split the webhook URL from WordPress and enter it separately in the Chargebee's web interface. While url is https://example.com?chargebee_webhook_call=true, the username is "admin" and the password is hgd765tgfrjhfdhjfhhf87587tgfh.
2} Thanks for pointing it to us. I've forwarded this to the respective engineering team, and they will update it at the earliest.