hi ninal98690845
just realised that you can't migrate directly to FederatedID (only AdobeId or EnterpriseID), see here: Migrate Analytics user accounts for Adobe IDs
to make things even worse, the migration from AdobeID to FederatedID is not "just a change of the authentification". according to Manage identity types in Adobe enterprise offerings the Migratiion from AdobeID to FederatedID will basically create a completely new account and then try to migrate the assets to the new account. according to the doc this migration can be performed by the user automatically, but sone cases need manual migration.
I strongly recommend to reach out to ClientCare if you can migrate your users directly to FederatedID.
remark: be aware that some functions can not be accessed by FederatedID, for example this forum 