1. Install the DR 16.2 and don't open it
2. paste this command in terminal
perl -pi -e 's/\x77\x39\x07\x0F\x1F\x44\x00\x00\x55/\x77\x39\x07\x0F\x1F\x44\x00\x00\xC3/g' /Applications/DaVinci\ Resolve/DaVinci\ Resolve.app/Contents/MacOS/Resolve

3. and if the app not open, back to terminal again and make sure you already install Xcode from terminal use this:
xcode-select --install
4. after that use this:
sudo codesign -f -s - /Applications/DaVinci\ Resolve/DaVinci\ Resolve.app/Contents/MacOS/Resolve