In your Opportunity fields you have a system field called Stage:

• Each Opportunity Stage has a matching Probability (%) value, you can see this under:
  • Salesforce Classic –  Setup | Build | Customize | Opportunities | Fields | Stage
  • Lightning Experience – Setup | Object Manager | Opportunity | Fields & Relationships | Stage

• When you set the value for Opportunity – Probability (%) in the RIO Inventory Configuration, this value is used to determine when inventory should be updated:
  • Opportunity – Probability % to Reserve: When an Opportunity reaches a stage at or above this Probability %, the quantity will be considered reserved, but will not yet be deducted from Warehouse Inventory.
  • Opportunity – Probability % to Commit: When an Opportunity reaches a stage at or above this Probability %, the On Hand quantity for the product will be deducted.