Hangouts

In general, google seems to have not supported older OS X system versions

and some newer than Mavericks 10.9.5 as well. IF that is where the Mac is at

you may be able to upgrade to El Capitan 10.11.6, Sierra 10.12.x or later.

Hangouts Help - Google Support

Official Hangouts Help Center where you can find tips and tutorials on

using Hangouts and other answers to frequently asked questions.

https://support.google.com/hangouts/?hl=en

For other items - this search has several - of which some actually may apply:

https://duckduckgo.com/?q=Google+Hangouts+Mac+help&t=ffsb&ia=web

Hangouts is a Google product. Contact Google for assistance with their products and services.

With third-party applications and other items that may be left behind,

their uninstaller may work to remove those parts that would be out of

date and leave residual clutter in your various systems.

The iOS devices and macOS (OS X) computer systems have some

commonalities as well as differences ~ I'm still learning how to use.

Easier to uninstall iOS apps by clicking and then they jiggle, click to

delete, in devices. (And as I'm not running latest MacOS in my Macs

they can be a bit different; and may leave some parts behind at times.)

OS X Lion+ : How to remove Mac App Store apps that appear in Launchpad - Apple Support

Some software makers are better at removal of older product bits when

a later similar product is installed; but do not count on it. Because of the

newer iOS and macOS, your record of purchases is in your Apple ID and

not necessarily in a device. (I see some old listed purchases in App Store.)

At near 1:30AM in this timezone, my thinking isn't so great & need sleep.

What version newer Mac system did you install? There were three newer

than Mavericks available; but only one would have shown automatically.

High Sierra macOS 10.13.x would have been in Mac App Store. While

older Sierra macOS 10.12.x and El Capitan OS X 10.11.6 have links to

get them within Support articles. ~ I've posted links to Sierra & El Capitan

several times in the past few months. A few of my replies had them both.

Depending on the hardware of the Mac, some systems worked out best.

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PS: There is this article which covers (or appears to) the Mac systems that

shipped with a Mac and the later ones that may be used in those models:

Use the Mac operating system that came with your Mac, or a compatible newer version - Apple Support

While this may not help you much, it's always a good idea to create and

use 3x backups; not just TimeMachine backups. Complete bootable clones

are best on higher speed ports and cables. As fast as possible if older Mac

because you can run a Mac from an externally enclosed storage drive if

the unit is correct & setup properly for its vintage. (Yet inadequacies occur.)

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In any event...

Good luck & happy computing! 🙂

There are several ways to upgrade a system in Mac that may leave

some older applications behind; so without knowing your method

or what you upgraded to from Mavericks 10.9.5, some would not

be compatible or would have refined (or reduced?) functionalities.

{..Tried to edit the above further, but thread finally timed-out instead..}

In any event..