Have more than 10 users for multi-factor authentication

We are very unhappy about the MFA policy. We are a ski club, and we have more than 10 coaches that send out emails to their respective teams. We don't understand how we can continue to use Constant Contact for communication if our coaches can't sign in to write their emails. We don't all share a common office, so trying to share MFA details between people, with a shared login seems nearly impossible now. (And FYI, a little more notice would have been good. Now I'm scrambling to set up enough accounts so that coaches can communicate in the next few days.)