After macOS Monterey update I can't access or create Word files

That's correct. However, depending on how dependent you are to MS Office there are a couple of free, open-source alternative apps, LibreOffice and SoftMaker FreeOffice 2018, that can open, edit and save MS Office files to the MS Office format or their own format.

Otherwise, as you've already been informed, you'll have to get a new 64 bit version of MS Office or the Office 365 subscription version.

I am reading this as you seeing your files, you're just not able to open them. Are you using Office365? If not, it sounds like the problem is you're using an old version of Microsoft Office that is a 32-bit version.

Please clarify so we can better assist you.

Microsoft Office 2012 for Mac OS has not been supported on later releases of MacOS since MacOS 10.13 (High Sierra). So yes, if you wish to continue to use Microsoft Office, you will have to purchase Office365.

Here's where you can purchase it from Microsoft:

https://www.microsoft.com/en-us/microsoft-365/buy/microsoft-365

Note: You can buy a one-time perpetual license for one computer that is not a subscription price. It's at the bottom of the site page from the link above. Looks like it's $249 and you'd never have to pay again.

The subscription portion is cheaper up front, and it allows you to install it on up to five computers, including mobile devices.

The "standard" Microsoft Office365 allows one to install MS365 on up to 6 PC's. That is $99/yr.

The one-license "personal" version only allows 1 computer. That is $69.99/yr.

So determine which one is yours. If it's the $99/yr subscription, yes you can download/install MSO365 and just enter your husband's credentials when you have to activate it and you're good to go.

https://www.microsoft.com/en-us/microsoft-365/buy/compare-all-microsoft-365-products

If you had an old 32 bit version of Office it won't run on Monterey. You need to upgrade to a 64 bit version of Office.

After updating to Monterey I can no longer use Word for MAC -2012 version and Microsoft tells me I have no subscription so mu st buy Word again

Can I use my husband's MS365? Or do I need to order ($249) my own on my new MBAir? Will my old Word documents open that I transferred over from my very old Air?

Your old documents will open in newer Office version.

You have to check what type of MS35 subscription your husband has. Some can be used on more than one device but maybe not at some time.