How to use TeamViewer on my old Mac?

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I’m using a old Mac in my office, running OS 10.7.4. As my OS is old I cannot install new version TeamViewer, although I can install old version, but I cannot connect to newer version TeamViewer.

In the past, I’m using web login to connect to my home PC, with my old FireFox ver 48.0.2, it is fine enough for me, but suddenly, about 2 or 3 weeks ago, TeamViewer website told me that my browser is too old to login.

But problems is I cannot update my browser as my OS is too old.

So anyway I can use TramViewer on my old office Mac now?