Working as a freelance translator for multiple organizations in Groupshare

I've been working with an organization as a freelance translator and used to have access to their Groupshare server-based resources. That organization changed ownership recently and the new owners no longer have access to Groupshare nor to my account. I now have a new client who tried to add me to their Groupshare organization with my email address, but they got an error message saying they couldn't add me because I already have an account (with that other org who can't access it). What can I do to access that new client's server-based resources?