To invite Page followers to a group:
Log in to Facebook, then click your profile picture in the upper right.
Click See all profiles, then select the Page you want to move to.
Go to facebook.com/groups and select your group.
Click Invite, then click Invite Facebook Friends.
Enter the name of the Page follower you want to invite to the group, click their name, then click Send Invite. You can manually invite up to 1,000 contacts per week.
To turn on automatic group invites to followers who have recently interacted with your Page, click next to Auto Invite, then click Confirm.