Sometimes it is helpful to navigate direct to Dynamics Admin Portal, without entering the Office 365 portal. For example: I had the case, the redirection from Office 365 Portal to Dynamics Admin Portal does temporary not working. Or if you have a demo environment and the Office 365 portal contains no link to Dynamics Admin Portal.

For instances in Europe, Middle East and Africa (EMEA) region, you can use the following link:

https://port.crm4.dynamics.com/G/Instances/InstancePicker.aspx?Redirect=False

For other locations, you must replace the *crm4* into your region URL. You can find the information in article: List of Dynamics 365 Online regions