1οΈβ£ Click SETTINGS
2οΈβ£ Click NOTIFICATIONS
3οΈβ£ Go to LIKES and change it to don't notify me.
4οΈβ£ Go to NOTIFICATION EMAILS and change it do daily or whatever frequency makes sense for you.
5οΈβ£ This is where you can also change other settings for the group. Check the other settings to see what you might want to change.