This is the new version which comes out each year. Installing this major upgrade now will make STP and PAYG updates easier and smoother later in the year, as they will most likely by updates to the 2018 version only. So this has to go on first, anyway.
Updating to Reckon Accounts 2018 now still contains the tax tables for the financial year 2017-18. Near the end of June the 2018 Tax Table Update will be released to update PAYG taxes and thresholds to the new levels for financial year 2018-19. STP will be included in the 2018 Tax Table Update.