You can reach out to the clients via the "public message" board that is available on Public projects and projects you have been invited to. You can ask questions on this board and then submit your proposal for the project accordingly. However, we do tend to encourage the experts to submit a proposal for the project to increase the chances of the client reaching out to you. You can always withdraw your bid at a later date if you wish.
Please reach out to us via email at “contact@kolabtree.com” if the above does not answer your query.