Hey Jennifer,
you no longer need the mt_prep_gamma_snap script that has circulated around this forum.
if you clone the github for the stamps 4.1b release a new script called mt_prep_snap is in there.
run this script in your INSAR_masterdate folder with the following command:
mt_prep_snap MASTERDATE FULL_location_insar_masterdate_folder/ DA
DA is normaly between 0.4 and 0.42
check the StamPS manual and also this gitlab for extra help: https://gitlab.com/Rexthor/gis-blog/blob/master/Documentation/StaMPS-2_Workflow.md
Greetings,
Gijs