Once a project is posted, Voice123 sends out invitations to a project in two stages:
First stage - your profile's preferences and the project requirements match.
Second stage - Your membership level and the percentage of your proposals liked by clients.
That means, if you pass the first stage, Voice123 will look through all the voice actors and rank them by membership and how well they rank within the percentages of proposals 'liked' by clients.
Depending on the number of invitations requested by the clients, you will or will not be invited.