Background
Salesforce now requires that connected apps either be installed into the org or the user have special permissions in order to use a connected app. For more details on this change, see Prepare for Connected App Usage Restrictions. Since Report Sender requires a connected app to get your report data from the API, this affects Report Sender.
Impact
If the connected app is not properly configured, users may encounter this error when creating a schedule and attempting to authorize Report Sender.
Solution
In order to allow users to use Report Sender, two things are required:
They must have one of the CloudAnswers Report Sender permission sets (Admin or regular, depending on their role).
The CloudAnswers Report Sender connected app must be installed into your org. Note: This is different from the AppExchange app, the connected app is something you install in your org.
Both of these steps are covered in the installation guide.
Installing the Connected App
Before completing these steps, a System Administrator or user with "Connected Apps OAuth Usage" or "Use Any API Client permission" must first authenticate Report Sender by going to the Report Sender tab and clicking New Schedule and approving access.
After that, follow these steps to install the connected app for other users:
In Salesforce, go to Setup > Connected Apps OAuth Usage.
Click Install next to CloudAnswers Report Sender.
Click Install again