When you receive an invite to join a board or have been given a link to join a board you do not need to be a paid subscriber of Ideaflip.
Ideaflip is built for collaboration but it is also secure so you do need to be a signed up user of Ideaflip but not necessarily a paid subscriber. We do not currently allow anonymous users.
When you join an Ideaflip board for the first time you will be asked to sign-up with your email address and name. At this point, you will be asked if you'd like to trial a subscription so that you could experience an unlimited service. You do not need to accept this invitation and can go directly to the board you have been invited to.