Teams on older iMac

No. According to MacTracker, the last supported version of macOS for a 2014 iMac is macOS 11.x Big Sur.

FYI, even systems running Monterey will likely stop receiving support from MS once macOS 15 Sequoia is officially released in a month or two since Apple will officially stop supporting Monterey & many developers follow along as well (at least for any newer releases of software).

Not sure if you know or not but a 2014 is considered pretty old at 11 years old now. It is also considered obsolete (as it cannot run current versions of Mac OS) and Apple has classed it as a "vintage" meaning parts are no longer available. If this machine is a "daily user" then I would recommend replacing it sooner than later before it begins to have hardware problems.

This might work https://support.microsoft.com/en-us/office/use-microsoft-teams-on-the-web-33f84aa9-2e8b-47ac-8676-02033454e385 - try different browsers until it does.