The warning indicates that your application server is running out of space. See https://docs.mendix.com/howto50/monitoring-application-health
I would not worry about log files and such rather check the root causes for your disk usage. Does your application creates file documents and if so are they cleaned up properly after deletion?
The Application Storage does not refer to the team server or the Sprintr portal. The Application Server is where the Mendix runtime is deployed and where the object cache and file storage is done. When this error occurs, it nearly always indicates that there are too many large documents stored in the Mendix app. PDFs, Excel files, and other imported documents do not live in the database as BLOBs. They are stored on the application server file system. Does your application generate lots of PDFs? Maybe you can implement a document cleanup to remove older files and free up space. Alternatively, you could look at an integration to an external file storage like Amazon S3. Mendix can also add additional file storage space to your application server for an additional cost, but in the long run that space will end up filling up as well.
You can take a look at https://appstore.home.mendix.com/link/app/54339/ This Module greatly helps in analyzing your file documents. This analysis can then help you figure out which documents you don't need and handle appropriately