External Bootable Drive will not install IOS

Before getting to the above screen where I need to choose the drive, as per the instructions from Apple (https://support.apple.com/en-us/HT201372) I changed the startup disk in my System Preferences to the Samsung T7 SSD as my startup disk so that I can attempt to install the macOS High Sierra that is downloaded to the external drive, however not yet installed on that external. then restarted. The Macbook then restarts in MacOS Utilities and gives you 4 choices.

Of course I can choose the Macintosh HD, but that is not where I need to go. As per the instructions from Apple (https://support.apple.com/en-us/HT201372) for creating a bootable external drive, I need to install High Sierra on the external to use it as a bootable disk.

I have tried both. I tried the erasing the entire drive and reformatted to Guid macOS Extended (Journaled) and then I tried reformatting to APFS. Neither worked. I then googled which would be more appropriate format for a bootable disk running High Sierra and I found instructions from Apple (https://support.apple.com/en-us/HT201372) scroll down the page to this

"Use the 'createinstallmedia' command in Terminal

1. Connect the USB flash drive or other volume that you're using for the bootable installer. Make sure that it has at least 12GB of available storage and is formatted as Mac OS Extended.
2. Open Terminal, which is in the Utilities folder of your Applications folder.
3. Type or paste one of the following commands in Terminal. These assume that the installer is still in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume...."

This says it must be Mac OS Extended (journaled), however, after trying both APFS and what is instructed by Apple, I get to the same stumbling block, neither format works.

I would like to make a bootable external hard drive with High Sierra on it. As it is now, I am following the instructions from Apple https://support.apple.com/en-us/HT201372 to try and create this bootable drive, but I can not figure out how to actually install High Sierra on the external drive. I have the install file on the disk, but have not been able to install it. Am I dreaming to think that I can run my 32 bit programs this way? Here is another set of instructions similar to the Apple instructions on how to achieve actually running a different MacOS from an external hard drive.

https://www.macworld.co.uk/how-to/mac-software/macos-external-drive-3659666/

In the end I may need to install a program called Parallels in order to use my 32 bit programs on my 2020 Macbook Pro that currently runs 64bit Catalina. https://www.parallels.com/blogs/run-32-bit-on-mac/

Yes, I boot the computer to the MacOS Utilities screen. I choose the Reinstall MacOS. When I get past the next 2 screens and it asks which drive, I choose the external hard drive. That is where I run into trouble. I will get a little icon that says that the External HD was locked. I am going try to install it using the USB stick as you suggest and will let you know how that works.

Yes, I boot the computer to the MacOS Utilities screen. I choose the Reinstall MacOS. When I get past the next 2 screens and it asks which drive, I choose the external hard drive. That is where I run into trouble. I will get a little icon that says that the External HD was locked. I am going try to install it using the USB stick as you suggest and will let you know how that works.

No, I kinda gave up for a while, but I am determined to figure this out. Why else would Apple and the tech at Adobe suggest this as a working option? I am just missing something, and it's probably something small.

https://support.apple.com/en-us/HT201372

Until I find a work-around for my new 2020 Macbook Pro, I have resigned myself to using my 2011 Macbook Pro for running High Sierra and my Adobe CS6 Master Suite. I paid so much money for that Adobe program that is 32 bit that I am not willing to transfer over to the subscription programs that Adobe now offers. However, It still sucks to have to haul 2 laptops with me.

Thank you for your input adfit11.

https://support.apple.com/en-us/HT201372

This is how far I get. (cannot do an actual screen shot in this mode)

I have tried it both ways, but I am going to try it again. Thank you.