1. create a user on Synology nas: pinas
2. On raspberry mkdir a directory: NAS2
3. mount:

sudo mount -t cifs //192.168.178.25/home /home/pi/NAS2 -o user=pinas,pass=xxxx,uid=1000,gid=1000,dir_mode=0700,file_mode=0600,vers=1.0

or add to /etc/fstab:

//192.168.178.25/home /home/pi/NAS2 cifs user=pinas,pass=xxxx,uid=1000,gid=1000
,dir_mode=0700,file_mode=0600,nounix,vers=1.0 0 0