Admins can set your system to only allow for certain file types and sizes on an account-wide level
By default, Cirrus allows files up to 1GB to be uploaded to your Cirrus account.
You can fine-tune the size of files you accept in 100MB increments. You can also Optimize PDFs in Cirrus, and set a threshold in MB for what file sizes are optimized.
For how to set Expected File Types and Sizes on a Doc Title-level, please see this article.