Offer to help setup the account and show them how to use Mastodon in general.
Also, not necessarily applicable to you but worth keeping in mind: encourage organizations to run Mastodon instances in addition to providing email addresses. If an org is providing email to employees or members for business correspondence they could easily provide Mastodon services as well, this allows members to have public discussions in twitter format without a third party controlling the platform.
Finally. Are they actually hiring decent UX folks this time or are they using the people who designed 1980s VCR programming UIs again?