Corrupted prerequisites (Visual C++ Redistributable for Windows). Solution: Manually install vcredist_x64.exe from Microsoft (2015-2019 version) and rerun the Lightroom installer.
If you want to keep older versions on your machine, click "Advanced Options" during installation and uncheck "Remove old versions". System Requirements
Antivirus software quarantined a core AI file. Solution: Restore from quarantine and add the Lightroom CC installation folder to your AV exclusion list. adobe photoshop lightroom cc 2019 211 install exclusive
Intel® or AMD processor with 64-bit support; 2 GHz or faster processor. RAM: 4 GB minimum (8 GB recommended).
If you have a fast external SSD, change the to the external drive to save space on your primary boot drive. System Requirements Antivirus software quarantined a core AI
Summary
macOS v10.12 (Sierra), v10.13 (High Sierra), or v10.14 (Mojave). Processor: Multicore Intel processor with 64-bit support. RAM: 4 GB minimum (8 GB recommended). RAM: 4 GB minimum (8 GB recommended)
Adobe Photoshop Lightroom CC 2019 (v2.1.1) Installation Guide