The option to "Allow" the third party driver will only be available for a short time (maybe 10-15 minutes). I would try restarting the Mac and checking the Privacy & Security System Settings immediately after booting to see if you have the option to "Allow" the Olympus software. Remember if you are using an Apple Silicon M-series Mac, then you must first reduce the security by accessing Recovery Mode as listed in the Olympus instructions.
You may need to reinstall the software to have it trigger macOS to show the "Allow" button again....just make sure you have done everything else first to reduce the computer's security if using an Apple Silicon M-series Mac so all you have left to do it click "Allow" after reinstalling the Olympus software.
Make sure you are not using any anti-virus apps, cleaning/optimizer apps, or third party security software since they may prevent you from receiving the "Allow" button in the Privacy & Security System Settings. There is no need for these types of apps on a Mac since they usually cause more problems than they solve since they interfere with the normal operation of macOS. If you have those types of apps installed, then uninstall them by following the developer's instructions. Afterwards reboot the Mac to see if you get the "Allow" button....perhaps try to reinstall the Olympus software again now that those apps have been uninstalled.
If you are still having issues after using the Olympus instructions I linked previously, then you will need to contact Olympus for support.