The default REFramework uses Orchestrator queues to store and retrieve transaction items, which are the units of work to be processed by the automation. To use the REFramework without Orchestrator queues, one needs to remove or modify the activities and variables that depend on them. The Get Transaction Item activity is used to fetch a transaction item from a queue, and the SetTransactionStatus activities are used to update the status of a transaction item in a queue. Therefore, these activities need to be excluded from the project.
Additionally, the variable type of io_TransactionItem needs to be changed from QueueItem to a suitable data type that represents the transaction data, such as DataRow, String, etc. (UiPath Automation Developer study guide) References:
REFramework without Orchestrator
REFramework documentation