change VB.net application from Network to Sharepoint

We have a mature VB.net application which uses Network storage. Our central IT support have unilaterally moved our network files to SharePoint, and we need a few key modules written in VB.net (2019 or any earlier version). No third party libraries - but any MS .dll is fine. 1. Connect to a SharePoint web folder. 2. Copy a Sharepoint file to a local drive. 3. Copy a local drive file to the Sharepoint Folder. 4. Close the connection and clean up.