We understand you are having a problem accessing the Mavis Beacon Skill Checks on OS Sierra and Higher.
Please do the following to resolve the issue:
Go to Macintosh HD - Users Folder and then the Shared Folder.
Inside the Shared Folder, there is a folder named MBTTUkey. Please delete this folder.
Download the zip file MBTTUkey.zip from this article.
Place the MBTTUkey folder from the zip file back into the folder named Shared.
The skill checks are now restored and the Skill check will be functional.