The Brother DCP-L2620DW does not support direct scanning to SMB folders (Scan-to-Network). As a DCP model, this function is not available, unlike the fax-capable MFC models in the series. However, scans can be transferred via FTP protocol or via the Brother software via USB/WLAN.
Important details on SMB support for the DCP-L2620DW:
SMB scan (network folder): Not available.
FTP scan: Available as an alternative to scanning to network folders.
Brother software/driver: Scans can be saved directly to the computer using Brother software.
Connection options: WLAN, USB and Wi-Fi Direct.
Printing: Supports PCL and PostScript.
Brother's DCP series is designed for high print speed and basic functionality, but this model does not include advanced network scanning features such as SMB.

You need to share the folder for scanning via wndows network share

We don't need that, but it should work.