I tried to donate $100 two years ago. My credit card was rejected, for no reason I could discern. Again today I tried to donate $100. The website first of all REQUIRED a donation of $5 a month. I hit the back button. I was then able to get it to accept a 1-time donation. But it would ONLY accept a $19 donation. So I made a $19 donation. I would think that one of the areas where LibreOffice would want to pay special attention, would be to be sure that you are not DENYING those who want to make a donation, as you are denying me.
The web page linked from LibreOffice site suggests a monthly donation but you can set a one-off payment, monthly, quarterly, or yearly from that drop down field on the page. AKAIK there is no limit on donations, you can enter any value by overwriting the suggested amount
This is not correct - if it were, it would be a major problem. When you download, you get sent to a page that starts the actual downloading (it might take some moments, while it chooses a good mirror to download from); and also it has a section asking for a donation, but it never requires it! (Pinging @cloph here, to inform that there might be a possible miscommunication/usability problem with wording/positioning/etc.)