The program crashes when adding a payer.

This is an issue with .net 4.7. We recommend you uninstall .net 4.7 and install .net 4.5. 

Also make sure the Windows patches are up to date.

If you are using the 2018 program and can't uninstall .net 4.7, then you can go to the utilities tab in the payer window and select "Mag V1" this will launch the old version of the program and you can do your work there.