I was looking for a donate button to the Zorin Project and that was not very easy to find. Only through forum search pointed me to the "About" page which contained a Donate button.
My suggestion is: Put a donate button in the upper header of Zorin Homepage.
I just canceled my eOS monthly donation payment and want to support Zorin OS instead from next month.
Maybe the Zorin devs like to keep donations a more low key affair, not like Bob Geldorf's infamous plea on the Live Aid charity event "Give us your ...money!".
The Avast devs have never been heavy handed or agressive money grabbers. The donations facility has always been low key. We have always indicated to new users asking here about the Pro paid edition, that it is the primary income stream that supports the development and maintenance of ZorinOS. I guess this still remains true and is being well supported.
Apparently, KDE has been showing a popup in the desktop asking for donations. This is a one-off that goes away after it's dismissed, but has had a massive impact:
I'm not too sure if I really like this, but open source projects are seriously lacking funding in all fronts. And it's as respecting as it can be in terms of privacy, screen real state...
Making the donation button more prominent in the website for Zorin OS alone would probably go a long way. Just think of all the people who are put off for the $40 price tag of Pro, but that might be willing to donate $1, $5, $10... etc.
At the very least, an article on the help section on how to donate (and why) might help. Even a few links to other open source projects that Zorin OS leverages might already help boost engagement.
Maybe a new section in the main landing page inviting people to read more about Zorin might be enough (quick mock):
If directly and persistently asking for donation is not what Zorin team would like to do, what about a button "How can you help Zorin"? And there one can list options, like (i) purchasing Pro version, (ii) donating any amount, (iii) showing Zorin OS to your friends/colleagues, ...
Maybe a subscriber-specific newsletter, too, to make it more enticing? Zorinews sounds nice.
I wouldn't mind donating a few dollars a month or a year, but getting something back (in addition to the main thing, of course) would be a nice incentive.
I admit it has to be a delicate balance. Done not right, it will be off-putting for some people.