Can you open the project to everyone? I'm new and I'm wishing to participate.

It is not a private project so i don't know why you can't access the project? It is open?

Do we have to put all the text in the poster, that is provided in the word file?

It is limited to designers that have 2.5 star rating on posters. If you haven't make any you can't submit a proposal because you don't have any feedback.