Linking Google Analytics Accounts

Linking your product accounts to an organization provides a number of benefits:

•   Linked product accounts and their associated user accounts are available from the Analytics 360 Suite.
•   Organization administrators can manage users in linked accounts.
•   Organization, account, and product pickers in the header are available from each product.
•   You can manage billing for those accounts in Organization settings.
•   When you link an Analytics, Tag Manager, or Optimize account to an organization, any organization user is able to create a new Analytics, Tag Manager, or Optimize account and link that new account to the organization during the creation process. Those new product accounts are subject to the original terms of service that you agreed to for the original account.

Prerequisites for linking Analytics properties is well documented in the support documentation linked below and is required to enable 360 service level at the property level.

A note here. If you have had a previous account before and would like to link. Make sure it is added to the GMP portal. 

Otherwise when the linking occurs neither side of the party will be able to see the linking requests in their portal.

References:

https://support.google.com/marketingplatform/answer/6308952