As @Jon_Smith highlighted: If you aren’t too familiar with the REFramework, simply go for a Linear Process in this case. However, the template’s Exception Handling is very valuable, so even for simple cases (when experienced) it makes sense to use the REFramework (or your own, improved version). You wouldn’t want to build the general Error Handling yourself.
Therefore, if you want to: Adjust the ‘If’-Activity/Condition to something like ‘in_TransactionNumber = 1’, so you can force the Process State to be executed only once.
You could add all your activities (download excel sheet and make changes to it) in the Process Workflow, or you could consider adding a ‘First Run’ mechanism to the ‘Get Transaction Data’-Workflow [download the Excel File, which is to a certain extent your ‘Transaction Data’]. (The ‘First Run’ is similar to how the Config is retrieved in InitAllSettings). In this case, your Process Workflow would only contain the changes necessary in your downloaded Excel File.
However, it seems to be a very simple process why you might not even need the REF. Then again, if your Automation fails for different reasons, you might be better off using the Framework (it would be good practice to learn how to adjust the Framework to your needs, too!).