To let Bugsee integrate with your Redmine, you should enable REST API access. Enable it in Administration -> Settings -> Authentication.
Supported authentication methods
Select "Basic authentication" in the first step of integration wizard. Click "Next".
Provide valid host (URL to your Redmine), username and password.
You can find your personal API key on your account page (https://<redmine-domain>/my/account) when logged in, on the right-hand pane of the default layout.
Start Bugsee integration wizard and select "Personal token" authentication type. Click "Next".
Provide valid host (URL to your Redmine) and paste generated token.
There are no any specific configuration steps for Redmine. Refer to configuration section for description about generic steps.