There are several ways to log into Dynamics 365 / D365.
To log into the Home portal, go to https://home.dynamics.com. This takes the user to the various Dynamics 365 apps available:

Selecting an app will log the user directly into the app.
Alternatively, a user can access the app directly from its URL. For example, change yourorg to your org – https://yourorg.crm.dynamics.com/:

Note in the url, “CRM” may change with the region.
