As a company admin, you have the ability to check your site for any users that have not yet accepted their invite. To do this, start by clicking on add From here, click team. We have a filter that we can select titled invited. This will display all the users that have been invited but have not accepted their invite yet into ExpandShare.
Clicking the three dots, you can select the reinvite option. This will send the user a fresh invite to ExpandShare, and you will see a confirmation at the top of the screen showing invite has been sent to this user's email. It's also best practice to remind these whenever you can, as these invites can expire. This is how you can ensure your users gain access to ExpandShare.