Examplify 2.7.4 or later is only compatible with Mac OS 11.1 to 11.4 (but not 11.5 as of 7/24/2021; Examsoft is testing DO NOT update to 11.5 if taking any exams between 7/24/2021 to 8/1/2021), a.k.a. Big Sur. For those Mac OS users that are still on older mac versions, i.e. Sierra, High Sierra, Mojave, and Catalina; then we recommend that you upgrade to Big Sur.

Also, Apple Support has an extensive upgrade guide. Visit link below.

How to upgrade to Mac OS Big Sur