Trouble adding users


I am trying to add internal users to my Smartsheet account (non-license users). I have sent the invites to people on my team. When they go to accept the invite, the link takes them to the Smartsheet homepage to create a new account as a free trial. From my end, it still says their invite is "pending" as if they haven't accepted it.

Does anyone have any suggestions on how to fix this? I haven't heard back from Smartsheet's help center. Thanks!