Getting license code for older 365 app

To obtain a license key for an older version of Office, you will need to contact Microsoft Support directly. Since you mentioned that you are trying to reinstall your old desktop apps, it's important to ensure that you have access to the original product key or the source files of the older version you wish to install. If you obtained your Office through a volume license, you can find the keys in the admin center in the product details panel on the Keys tab or request your keys through Microsoft Assisted Support.

If you are unable to access the admin center, you can find support phone numbers for volume licensing on the Microsoft website.

References:

• Find and use product keys for volume licensing
• Contact volume licensing support
• Upgrade your Microsoft 365 for business users to the latest apps
• Microsoft 365 Apps activation error: "You currently have not been assigned an office license that includes the Office desktop apps"

OK. How do I contact Microsoft Support directly? I can't find the link on the website.

You can often run recent subscription versions on an older Mac, but you won't be able to install the most recent update. On Ventura, you should be able to run version 16.100. See https://www.brandwares.com/bestpractices/2023/03/most-recent-office-you-can-run-best-practices/.

You can download the correct installation file from Microsoft's Update History page at https://quic.hkg1.meaqua.org/en-us/officeupdates/update-history-office-for-mac .