There are some issues that may crop up that can be resolved by following the below steps:
On joining the co-op, you should have been given the correct access permissions. However if you cannot access a document or sites, you need to login to your Google Account. You may need access to a specific group and if you don't have access, you need to contact the directors.
Logins not on tablet - workaround and then message on Loomio*
How to set up tablet and logins*
Work around for not being able to log attendance on TeamUp on tablet*