As a partner, sign into the Partner Center Dashboard as an Admin Agent.
*GDAP will automatically expire. After expiration, you will no longer have access and need to request it again.
Customers can approve your GDAP request in their Microsoft 365 Admin Center as Global Admin.
After you have requested GDAP access, the customer can approve your request. They simply click on the link in the GDAP invitation mail and will be directed to the Approve partner roles page in their Microsoft 365 Admin Center, where they need to Approve all.
Both you as a partner and the customer will get a confirmation mail about the GDAP request being approved which contains the Approver, Expiration date, Partner name and Partner roles.