Can anyone help me to resolve an issue with implementing a post-chat survey after ending a chat? 

After I end the chat session, I could see a 'Leave a feedback' button and it takes me to the new page but the created survey is not showing but giving an error.

Created all in the sandbox following the steps from https://chatbotslife.com/salesforce-surveys-in-embedded-service-for-chat-formerly-snap-ins-76224fb6729f#ee02

Followed by https://chatbotslife.com/salesforce-surveys-in-embedded-service-for-chat-formerly-snap-ins-76224fb6729f#ee02

1. Created a feedback (grabbed surveyId as of 0Kd***************)
2. Created a community (grabbed networkId as of 0DB***************)
3. Added required object relationships
4. Added Chat Survey Redirect controller & page through Developer Console, Apex Classes > Profiles, and Visualforce Pages
(In Community Workspaces, Administration> Pages > there was no selection as of 'Community Builder Page', so I just selected 'Default Page')
5. Added Post-Chat URL to Chat BUtton configuration as of
'https://livechat-fg.cs35.force.com/fashiongo/SurveyRedirectPage'
(Can I use Post-Chat Page as of 'SurveyRedirectPage' instead of URL? It doesn't matter to use either Page or URL for Post-Chat?)
6. Created Process Builders, saved, and activated.
 
Also checked the CSP and CORS however this error appears. 
livechat-fg.cs35.force.com refused to connect