Hi Abdulqadir,
I'm Dyari. Thanks for reaching out. I will be happy to assist you in this regard.
You can create folders in the system drive for saving data without affecting or damaging system operation, but it is not recommended.
It is safe as long as you have access to your computer. If you are somehow unable to get into Windows and it requires System Reset or clean installation, you may lose your data on that folder.
Therefore, it is best to save your data on a separate partition or you can use cloud storage like OneDrive or Google Drive for saving your data.
Please let me know if you need further assistance and keep me updated.