I want to share more details on how the storage server and scheduling server works. Once you schedule a test for remote execution, it is updated to the storage server and any change to that file will prompt Test Studio to try and update it. This happens even if the test is currently not part of a test list, which is scheduled for remote execution. I believe this is why you are prompted to upload the changes to the storage.
You mentioned that the scheduling and storage configuration are setup properly, but the Test Studio project can not establish a connection with the storage. Please check what is the execution status of the services and share a screenshot with me as well. Another possible reason for the encountered error is the connection status of the current Test Studio project. You need to connect it to "Run remotely" on the scheduling server and that should make the connection to the storage as well.
Please try the above suggestion and check the services. Let me know if the issue persists and share more details. I will do me best to help you resolve it.