I am facing an issue when I try to log in to Orchestrator, the pop-up message keeps showing up. Normally, after I click on the “Windows” button, it can automatically go into the orchestrator. Please advise how to solve it.
Welcome to the community
Looks like the user is logged out from the browser and hence you are seeing this
Cheers
Please share the screenshot of the popup/error for better understanding and solution.
Thanks,
Ashok 
Check with Orchestrator admin if the Active Directory login is enabled or not. If enabled check the machine you are using is granted access.
If the above points are good, then there could be chance that your machine AD password has been changed recently and older password still in cache somewhere. In this case check if your account is not locked due to invalid password, try to clear browser cache, temp folders and logoff from the machine. Login back and check if it works.
Found one forum post regarding this. You and Orchestrator can refer this if required.
Windows Authentication - Help / Orchestrator - UiPath Community Forum
Thanks,
Ashok