The action “Membership Grant Offer” will add access to the contact for a membership offer/product.
Keep in mind this will only send an email with login details if you have the template enabled in Membership > Email Settings. Otherwise, you would use an additional workflow with the Membership New Signup trigger for unique to membership login detail emails. Please see our other articles on memberships for assistance with this.
Please Note: Login details will only send the first time an offer is granted to a contact.