Clover Configurator can't be opened.

I've been following this sub for quite some time. Target machine is running z87 pro3 board. Got Hackintosh somewhat working only by booting to USB a while back. Got busy with life for a while and went back to winderps. I'm trying again tonight using the vanilla guide for Intel and get an error when attempting to open/run clover configurator. Exact error message is: "Clover Configurator" can't be opened because apple cannot check it for malicious software.... blah blah contact the developer. This rig is MacBook Pro 13" mid-2012 running MacOS 10.15.2. Apologies if this is a dumb question but I'm not very fluent with MacOS. What am I missing? How can I get the required Clover packages working as required by vanilla guide? Thanks

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Edit: I'm also trying to open Clover_v2.5k_r5103.pkg as a prerequisite of the vanilla guide and get an error stating: "Cannot install without ensuring the file system is read-write".