As for your previous question: TLS certificate issues can sometime stem from incorrect date settings as they are only valid between a specified timeframe, so if the TLS-Certificate is valid from 1.1.2021 until 31.12.2021 and your computer has some issues with it’s real time clock, you will get those errors. But as your time seems correct, in your case this is not.
Regarding the installation issues. How have you created the USB stick? Such errors often occur when there were some issues in writing the stick. After you have downloaded the Image from https://support.endlessos.org/en/installation/direct-download (and verified it!), use the Disks Utility to restore it to a USB stick.