You are now golden and about to get better.
Here are my revised notes from earlier, ignore the previous version.
Let's get your phone running!
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You have two choices.
I'm going to show you what TWRP has in Choice 1, then how I'm used to it in Choice 2.
Either one should work. They're totally different but ought to be fine either way.
Choice 1:
TWRP adb sideload will load and install a rom -
ADB Sideload | TeamWin
First get into sideload mode by going TWRP, Advanced, ADB Sideload, and swipe to get it ready.
Then you can just copy/move your rom zip file to your home folder using the Finder and just do this in a new Terminal Window:
adb sideload name-of-your-rom.zip
Watch the prompts on-screen, give it time, install rom, profit!
If you want to be sure of your rom zip name do this:
Open Finder, go to where you can see your rom zip file.
Open Terminal Window near Finder window.
In Terminal Window:
adb (spacebar) sideload (spacebar) {and now drag the rom zip file that you see in the Finder over to the Terminal Window and drop it - it will give a nice long name for it - and then just press return/enter}
Choice 2:
Personally, I prefer to do a push (because I know it better), see that the file got there and then just install normally in TWRP.
From TWRP main screen, choose Mount. At the bottom, you'll have a thing that looks like a label - but it's really a button - that says something like Internal Storage.
Tap that. Decide which storage you want to use, internal or sd card.
Back button on lower right to main TWRP screen.
Now - Advanced, File Manager
Look around and see how your storage areas are named by TWRP. Mine are named sdcard (that is really the internal storage lol) and external_sd (that is really the sd card). Go ahead and surf into either so you're comfortable.
Note the name of the one you want to use for your rom zip file.
OK.
Now move or copy the rom zip file over to your home folder. Using the Finder and drag and drop, or command-c/command-v, is just fine for that.
Then in terminal window (and notice that my example uses my external sd, by its TWRP name, you need to make the last bit match your needs) :
adb push name-of-your-rom.zip /external_sd
So, let's make sure that the syntax is showing up ok on your browser. I said:
adb (spacebar) file-I-want-on-phone (spacebar) name of storage folder according to TWRP with a slash in front
And yes, for the name-of-your-rom.zip file, you can also do the Finder to Terminal Window drag and drop trick I mentioned earlier.
When complete (and expect it to take some time), back out of File Manager to Advanced menu, and back in to File Manager - and now surf there to ensure that your copy was really ok.
Back out until main TWRP window, Install, profit!