You might want to try Viber (it has a video call feature on PC and OSX). There was also a beta of Jabber somewhere that had pretty decent video. And https://www.gruveo.com/ lets you call from your browser (it was so so for us, but maybe it will work better for you?)
I have been where you are, and i understand her perfectly, but just keep trying and offer a solution that works (maybe try it out with a friend beforehand?).
Hope it helped a bit :)
Try some of these:
https://www.makeuseof.com/tag/9-free-video-conferencing-web-apps-no-registration-required/
some need to "share a linlk" (email / text ?) others you just need to "Agree on a code" you know in order to join....
eg https://www.gruveo.com/
(i'm not ENDORSING this, it just may suit your use case.... there will still be SOME friction to join a call !!!)
> и ничего другого ставить не разрешают.
А и не надо. Есть https://www.gruveo.com/ и еще куча http://lifehacker.ru/2015/04/24/kak-zapustit-videokonferentsiyu/ - только браузер и веб-камера. Просто перешлите созданный канал (почтой, смс-кой, как угодно) и собеседник подключится.