The user enabled the Supply Allocation feature but wasn't able to locate the Order Management Dashboard. The navigational path Transactions > Order Management > Order Management Dashboard is missing.
1. Navigate to Setup > Company > Enable Feature
2. Under Items & Inventory > Inventory > Sales Channel Allocation = T
3. Click Save
Note: This feature won't affect any other features or performance if not used, but it is a prerequisite in order to use Order Management Dashboard. You could easily disable the Sales Channel Allocation via the same procedure.