Got "APP is not verified" Error on Macs Joshua Chang October 15, 2018 03:41 Follow Go to https://www.tiertime.com/downloads/software/, find the LKD File for MAC V x.x.x.x. Open UP Studio, choose Activate, and then load the LKD file. Related articles Chapter 1. Cetus MKIII 3D Printer Parts Introduction How to activate the printer How to fix the "USB device not recognized"in Up Studio? Comments 0 comments Please sign in to leave a comment.