The new Unified Interface for Microsoft Dynamics 365 poses a challenge to users switching from the Classic Web Interface - the Run Workflow option is no longer available. If you use on-demand workflows to help users get things done in CRM, this is potentially an issue.
The good news is there is a solution for this! First, the users need to be assigned a Microsoft Flow license in Office 365. Sometimes you'll get "Free" licenses along with other products (ie: Microsoft Office) - those work as well.
Next, you'll have to go into https://admin.powerplatform.microsoft.com/environments and edit the Settings of your environment. Once in Settings, expand the Product group and choose Behavior:
In Behavior, turn On the Show Power Automate option:
And now when you go to a record in D365 you'll see a new "Flow" drop down where you'll find your on-demand workflows: