Admins will not be able to set a password for an agent. However, agents can use the 'Forgot password?' option on the login page of the support portal. A password reset link will be sent to the corresponding agent's registered email address.
Please check the Spam folder in your mailbox if you're unable to find it. Alternatively, you can write to support@freshdesk.com for further assistance.
Here’s a video on how you can set it up:
https://www.youtube.com/watch?v=yj_xg4Xc-l8&list=PLsYJ3BsyR4qGFujlW0iDtOBOf4IPVsAqt&index=6