High level accounts cannot submit abstracts

Our website installed WP Abstracts Pro. We allow reviewers to submit abstracts. However, only users with the role of “Subscribers” of our website can make submissions. Users with the roles of “Contributors”, “Authors”, or “Editors” cannot even view the event dashboard. When they try to, the system shows “Your account is not setup to view this dashboard. Please contact your site admin.”

Our website must assign some users a role different than “Subscriber”. These users do not want to create a separate account only for the purpose of submitting abstracts. Please let us know how we can fix this problem. Thanks.