You can only add Figured Partner Organisations to your farm.
This simplifies the access process for organisations, as it removes the need to add multiple people individually to a farm, and gives them one place to maintain a list of their users.
Access rights are given to an organisation from within a farm. There is no way for a organisation to add themselves to a farm unless a member has existing personal user access to the farm.
To add an organisation to your farm, click on Settings > Organisation Access. This will display a page which lists all the organisations which have access to your farm.
To add a new organisation – hit Add Organisation.
The resulting form displays all the organisations available to add to your farm. Use the search box to filter organisations by name. Locate the organisation you want to add, click Give access, then select the permissions you want to grant to the organisation’s users.
Once this is complete, the organisation should display in your Organisation Access list.