@risperling if you have the most up to date OS on your Mac but you can't install TT that probably means it's stopped upgrading on Mac OS 13 (Ventura), in which case Apple is basically no longer supporting your computer as the latest OS you can download is out of support (v13 went out of support in Nov which is why Intuit dropped support also).
I survived with an iMac for a couple of years on an out of date OS (and did my taxes for a year on a laptop until upgrading), the risk is up to you, you'll not be getting an OS or security updates and other 3rd parties like Microsoft and Adobe will stop sending you updates also. For taxes you can either try HRB that does provide support for older OS versions, or switch to an online service such as Turbotax Online or FreeTaxUSA. For 2025 Intuit should be offering for you to switch from desktop to Online Premier version for no extra cost for Fed (state maybe extra - check smallprint), this offer should come up when you try to install it - tho I'm not sure if anything different for Advantage.
The other option is to explore a HW upgrade to get to the latest MacOS version, I have found the Mac mini with 3rd party monitors to be a good replacement for more expensive iMac.
