Per the developer’s website, IvyBackup is available as a Home Edition, Standard Edition, or Professional Edition. Based on the price, the edition offered on SoS is the “Standard” edition ($42). The Standard edition does not do “incremental” backups.
For several years, the (Standard edition) has been offered on several Giveaway sites, and each time, the terms “incremental and differential” are listed in the features, however the Standard edition given away does not do “incremental” backups. When the developer is asked about these statements, he has always dodged the question, or given a partial answer that never gives the full details.
The program saves the backups in a Zipped format. If you do a search on “how to do incremental backup using 7-zip” you can accomplish the same thing.