Hi, Guys.
Hoping there's an Acrobat whiz on list who can tell me how to combine
separate .pdfs into a single document. I can't work out how to do it,
and the process (at least for me) isn't very intuitive.

Thanks,
Dani

Dani,

I can't help you with Acrobat Pro, as I don't have it.  If it gets to the point where you'd like to try something else, say so, as I can discuss PDF Split & Merge (PDF SAM) which has actually become accessible (or at least much more so than it once was) and the free version makes it easy to merge multiple PDF files into one.
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Brian - Virginia, USA - Windows 11 Pro, 64-Bit, Version 22H2, Build 22621; Office 2016, Version 16.0.15726.20188, 32-bit; Android 12 (MIUI 13)  

It’s not lack of contact with the world off campus that leads to the liberal views common in academia — it’s being trained to think critically and practicing this craft daily as we look at the world around us that makes us the libs conservatives so dislike.

     ~ Eliot A. Brenowitz, Seattle; New York Times, Letters, Tales of Town and Gown: Is the Campus Isolated?, August 20, 2022

PDF Split and Merge, PDFSAM, is a great little utility for doing exactly what its name implies.  The free version is generally more than enough firepower for all but those dealing with PDFs professionally and in large volumes of files.  There are several different variants of PDF SAM Basic:

1. 64-bit MSI installer
2. Portable ZIP archive

If you decide to go the installable route, pay attention during the install as there will be an offer to install Pro for a trial, and if you don't want Pro at all unchecking the checkbox for that avoids the trial.

Overall it's pretty accessible, and although the documentation talks a lot more about drag and drop for collecting your files, once you are in the Merge Pane you can use CTRL + A to add individual files which causes a typical open dialog to appear for you to navigate to the file you're trying to snag.  The order in which you add them is the order in which they will be merged, with the first file being the start of the final PDF, second coming right after, etc.  If you happen to get the wrong order, you can go into the file list that's been created, gain focus on one of the files, and the Remove (ALT + R), Move Up (ALT + U), and Move Down (ALT + D) buttons become available.  There is also a Clear button (ALT + C) that allows you to wipe out the entire list you've put together and start afresh.

There is a Destination File box where what it's name implies, the final destination for the merged output PDF, will be placed.  There is also a Browse button beyond that, and I generally use that and name my PDF to my liking in the Browse dialog for where the file will be placed when created.

There are many more options, in the Merge Pane and overall, but I am focusing strictly on Merge for the purposes of this discussion.  Even just getting the software, firing it up, and playing around a bit will allow you to explore the many things you might do with it.  

For myself, I've primarily used it for merging multiple PDFs into one, with occasional secondary splitting of a PDF into several individual files.
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Brian - Virginia, USA - Windows 11 Pro, 64-Bit, Version 22H2, Build 22621; Office 2016, Version 16.0.15726.20188, 32-bit; Android 12 (MIUI 13)  

It’s not lack of contact with the world off campus that leads to the liberal views common in academia — it’s being trained to think critically and practicing this craft daily as we look at the world around us that makes us the libs conservatives so dislike.

     ~ Eliot A. Brenowitz, Seattle; New York Times, Letters, Tales of Town and Gown: Is the Campus Isolated?, August 20, 2022