You can download the files here:
https://mega.nz/folder/pMMhCALK#e74H2nGjrUPEe2ta3iGfzA

Note that if you have already installed esp32 espressif via Arduino Boardmanager, you must uninstall it and then extract espressif.rar into Arduino\hardware folder.

I used this website to download the HK-ESP32 CAM (chinese board) files from Baidu: https://imwcr.cn/api/bdwp/ Baidu links found at: https://hkdoc.readthedocs.io/en/latest/source/Arduino/ESP32Arduino.html -- [espressif.rar] -- https://pan.baidu.com/s/1BXT0BUuBzCrGQT9FAb5qXw -- PW: 8ita -- [Arduino HK...