Relay enables collaboration by sending messages between accounts.
Linked users is a totally different concept, in which a user in one account can be invited to work in another account. It acts as a single sign on from one account to another.
Linked users should not be used with Relay, and are likely to cause errors if you attempt to use them. Linked users obscure the separation between accounts, and invitations are not typically enabled on Relay services.
In the interests of completeness, there is a brief account of how to set up linked users below.
The linked users feature requires that the account authority (the "accounts" account) has an invitations folder and a binding to this in their high-level package, and a binding for a suitable account action to accept the invitation.
To access linked user features, go to the Account manager find the row with Primary user group, and from the Action drop-down on that row, select the Manage connections option. Note that this is unrelated to the Manage connections Relay folder option described in Assignment and to Connection requests.
This will open the connections page.
The Action drop-down has two options: New invitation and Accept invitation.
New invitation allows you to enter the name and email of person you want to allow into your account, with some invitation text. You also need to select the owning user group into which to put them, whether you want to connect to their account, and whether to send them an email. Use Submit to submit.
This will give you a code to send to the invitee, and optionally send them an email.
Accept invitation allows you to enter a code sent from another account, view the invitations details, and then confirm the invitation. Depending on the options set by the inviter, this may involve you inviting them into your account too.
Once an invitation is accepted, a user is created in the inviter's account which acts as a proxy for the invitee user. This user can be granted permissions like any other user.
You can see the state of sent invitations and current connections from the connections page. You can click on connections to disable or re-enable them.
Once you have accepted an invitation, if you are signed into your own account, then when you access pages from the other account you will access them as the proxy user, and will be able to see the account.
A linked user account is just a convenience for not signing out and in again. It does not give you cross-account access, for example you cannot copy data from one account to another.