Share the folder on your mac as usual.
On ubuntu, set up Samba client.
sudo apt-get install cifs-utils samba-common samba winbind
To mount up partner
First, let’s create a directory to attach our Mac share to:
sudo mkdir -p /mnt/tmpshare
…and now connect our share to that new directory:
sudo mount.cifs //mac_ip_address/shared_folder /mnt/tmpshare -o username=mac_username,nounix,sec=ntlmssp,noperm,rw
You will be prompted for a password .... Enter your mac password and boom.... it is done!
To view the shared file,
cd /mnt/tmpshare
ls -ali