Some people consider what Rojava was as anarchist or at least anarchist-adjacent and considered it one of the closest models to what a large anarchist society could look like (it was recently dissolved by force by the new Syrian government). It had ~4 million people. The Zapatista territories consist of ~300k people and controls roughly half of the state of Chiapas (larger than some small countries).

https://www.reddit.com/r/DebateAnarchism/comments/ny5q74/where_do_tanks_come_from/ has been debated to death so check out this link's comments for far more well-written explanations of how big industry like military happens, and of course defense.

I don't see how transportation and hospitals is going to be harder under anarchism. Tons of people aspire to be doctors including children who've no concept of monetary value; all those medical dramas weren't for naught.

The most popular replacement for capital markets is personal interest and https://en.wikipedia.org/wiki/Gift_economy . https://anarchistfaq.org/afaq/sectionI.html#seci413 ? Well, do you want to do your chores? Probably not. But still, somebody has to do them, so eventually you do. Especially in damnedentireanarchist country, where people know how to stand up and have historically done so to overthrow a government.

Education administration would be the same as any other organization under anarchism, but there is a good question here about curriculum. The short answer is that the educators would decide on their syllabus and of course their curriculum as well. Of course, broadening views would be better, so like other organizations under anarchisms, different schools can schedule councils that they send rotating delegates to. (Anarchism is the abolition of hierarchy, not necessarily organization.) In general, standards can also still exist under anarchism. For how that works out you can take a look at protocols in open source and other open standards.

They start buying votes with favors?

votes?

decision makers

(English) Wikipedia can be looked onto as an example. It's fairly anarchistically organized (except, of course, its military is the Wikimedia Foundation's legal department, which isn't applicable to an anarchist society. for what is applicable see first paragraph). In summary, enwiki https://en.wikipedia.org/wiki/Wikipedia:Consensus is built through discussion logs that are summarized by someone people trust who hasn't participated in the discussion. That summarizer decides what arguments are most grounded in community norms and then which arguments are more popular to decide what the consensus is (or isn't. "No consensus" is an option. People are aware they can't just bash at a brick wall, too, so if there's an urgent-ish problem they know to eventually agree/concede on something.). You can also do reviews—a discussion where another independent summarizer uninvolved with both discussions will summarize whether the community thinks the initial summary was reasonable.

There is an extension in applying this to society: If anyone opposes (not just disagreeing while conceding) with that summary/decision, they may instead form a different association for the purpose of this task and execute their vision elsewhere.

Road repairs?

This is actually the most well-known example of socialism in action in a capitalist society, only surpassed (by miles) by libraries. Besides usual sewer socialism where the government focuses on public works, there's independent direct action like https://en.wikipedia.org/wiki/Portland_Anarchist_Road_Care where anarchists, fed up with broken roads, "illegally" fixed them themselves.

How is it decided that someone has too much

Property doesn't exist.

Assuming the question means "What do we do to those who don't want to follow anarchism?": https://anarchistfaq.org/afaq/sectionI.html#seci57 . TL;DR: No "taxes" but no communal services for you either. Crime would be dealt with as crime. People who work against a social structure kinda get ostracized no matter if anarchism or capitalism, and in anarchism where the social circles are the government (as far as provision of services is concerned), ostracism is far more severe.

An interesting case study is DAANES, whose "democratic confederalism" adopted many ideas from libertarian socialism—the most mainstream school of anarchism, and the one I'm talking about—and whose participants sort of conceded to see how it works out. Social and educative forces are far more compelling than you might imagine.