As a heads up, the launchSettings.json file adds MeetingsConnectionString as an environment variable (with the value "aaa"). This overwrites the same variable set in the appsettings.json file as specified in the Configure connection string instructions. It wasn't abundantly clear that this was the problem so it may be worth removing this variable from the launchSettings.json file or updating the instructions to get the user to update this variable in thelaunchSettings.json file, rather than the appsettings.json file.
As a heads up, the launchSettings.json file adds MeetingsConnectionString as an environment variable (with the value "aaa"). This overwrites the same variable set in the appsettings.json file as specified in the Configure connection string instructions. It wasn't abundantly clear that this was the problem so it may be worth removing this variable from the launchSettings.json file or updating the instructions to get the user to update this variable in thelaunchSettings.json file, rather than the appsettings.json file.