Yes, I was merely offering an observation that I’ve seen similar behavior before in the last version that I did test.
I’m gone ahead and Upgraded a sandbox instance of mine from 20.10 to 21.10.2. The instance already had Windows Authentication configured in Orchestrator and Identity prior to the upgrade.
Check your Traffic Inspector in your browser when attempting to login, there should be a request for https://<fqdn>/identity/ExternalIdentity/tenants
that returns a list of Tenants. Confirm whether this endpoint is returning any results. If there is no Active Tenant I would expect it to return an HTTP 400 with a JSON payload containing an error.
Although UiPath has improved the AD caching of Groups and Users it can still sometimes be slow depending on your AD/Network configuraton, as such it might be delaying the listing of available tenants (Can review your Windows Event Logs on the Orchestrator host for any errors)
With a fresh install there are two tenants that are available one called “Host” which I wouldn’t expect to see listed in selection list and the other would be “Default”. If you are not seeing that try visiting https://<fqdn>/identity/management/authsettings
directly to see if you can adjust your authentication settings, depending on how you setup user access.
- When you configured Active Directory did you also check “Force automatic login using this provider”?
If you do have it auto-signin, you can go into the Orchestrator database and modify the `AuthenticationScheme=Windows.Scheme record in the identity.ExternalIdentityProviders table and update the Field IsExclusive from True to False followed by a restart of your IIS Site.
After that visit https://fqdn/identity/admin
you should be re-greeted with the basic login form which you can change the Organization from Default to Host and login using your Host Admin User to access the Identity Management Hub.
Keep in mind that there are two Admin users which are separate credentials. One is the Admin for the Host tenant and the other is Admin for the Default tenant.

Select Orchestrator App to be taken to the Host Tenant view, here you can review your available Tenants, Licenses and default settings that apply to new tenants or the host in general.

Let us know how you make out.
Some quick URL references
- /host/
- /identity/admin/hub/
- /identity/management/