Im having this same issue as well on my Mac.
" “2021_DirectLink-SketchUp_Twinmotion_SU17-21setup.pkg” can’t be opened because Apple cannot check it for malicious software."
I almost forgot that Apple and Epic are in a big massive lawsuit and Apple is doing everything in its power to make anything that EPIC makes nearly impossible to use. Hard to believe that Fornite Mobile is the reason I cant do ArchVis. Petty