Telltale hasn't updated their blog yet, but it seems Law & Order: Legacies episode 4: Nobody's Child and episode 5: Ear Witness for PC and Mac got a surprise weekend release. People who purchased the season package from the Telltale store can open Law & Order: Legacies on their computer and select the episodes right now from within the program itself.
This brings the computer releases up to date with the iOS releases. There's still two more episodes left in the series, which will be released in the upcoming months.