You can manage user accounts in Expensify with Groove.id.
In the Groove.id console create a new Expensify app.
To configure Expensify, log in to Expensify.
Choose the policy you wish to manage, then People, then Invite.
Enter firstname.lastname@example.org for Email, Policy Admin for Role, and click Invite.
Copy the Policy Joining Link and paste it into the console.
Configure your domain
If you have your domain configured, which is typical, you need to check that your settings are compatible with Groove.id.
Go to Settings > Domains and choose your domain.
Choose Domain Admins and enter email@example.com for Email or Phone and click Add Admin.