FieldLynx has two settings for attempt numbers. If you want to use a cut then use the top option as shown here with 3 attempts, 6 athletes that make it through the 'cut', and a further 3 attempts for those 6 athletes.
Please note that when a cut is used, as per World Athletics rules, the throwing order will re-order in the 4th, 5th and 6th rounds, there is no way to stop this!
The second option is the bottom selection "Attempts" here you can set up to 6 attempts and this will not reorder or cut the athletes. Leave the Qualifying mark and qualifying athletes unticked unless you are running a qualifying pool.