Following the public docs Deploy the Resource Scheduling Optimization Add-in for Dynamics 365 Field Service there is a note "It may take several hours between the time the subscription appears in Microsoft 365 Admin Center and Power Platform Admin Center."

https://learn.microsoft.com/en-us/dynamics365/field-service/rso-deployment

In our case, after purchasing the license, it took between 12 to 24 hours for the add-in to appear in the Power Platform Admin Center. This delay felt excessive, and we believe the documentation could be improved by clarifying that the wait time may extend up to 24 hours. The term "several hours" is ambiguous and may be interpreted by users as 2–3 hours, which can lead to confusions delaying customer timelines.