The On-Page editing mode is currently not functioning in EpiServer, but instead you can use the preview option in the menu at the top right: 

1. Publish the page and blocks if they are not yet published. 
2. Click the 'Options' menu again. Choose 'View on website' to view the edits you have made.

Alternatively. you can also go to https://prep.hoyavision.com/xx Replace 'xx' with your country code.