socialist party in australia

I believe this is the article you're referring to: https://www.marxists.org/archive/lenin/works/1913/jun/13.htm

If that's the case, I can possibly answer questions on it.

1. he says the unions in australia are all capital serving and non-socialist, but he doesnt say why

Lenin is stating that organized labor in Australia at the time is Liberal. They've organized for collective bargaining assumedly, but they are reformists and do not seek Socialism as a rule. Take for example a number of other "unions" in the modern world. They will ask for more pay and for the private owners of companies to respect pre-existing labor laws, but they do not ask for the workers to gain ownership of said companies, or for Socialist policies in regards to democracy.

In that way, the unions at the time are more or less serving the interests of Capital in that they are willing participants in a newly forming Capitalist society, and only seek to reform portions of it while not challenging the power structure. In short, the unions do not yet represent a Socialist cause and want to work within the guidelines set by the Bourgeoisie. Lenin would probably say, based on this article, that the lack of independence in Australia at this time and the youngness of Capitalism there has yet to grow the environment where Socialist structures would arise in the first place.

2. he says that after capitalism develops in australia, a socialist workers' party will be created. why did this not happen?

For one, there were and are Socialist-centric parties in Australia. They just have not succeeded in their expressed aims. 

But this is more of a theoretical question so I'm going to answer it a bit differently. Lenin is working off of a Marxist analysis of Australia at the time. He is saying that the state is too young, industry too freshly implanted and grown, for the full establishment of the bourgeoisie and the alienation of the workers under fully formed Capitalism, and the further development of Socialism as a consequence. That is to say, in 1913 at the time of his letter, when Australia was 12 years old from its founding as a commonwealth nation and not just a dominon of the British crown.

In the Marxist view, the development of fulyl developed Capitalism and industrial society is a predecessor to the rise of Socialism as a consequence of workers being exploited under that system of abundance. If you want a quick overview of this written better than I could explain it, check out this essay by Engels:https://www.marxists.org/archive/marx/works/1847/11/prin-com.htm

So, why has a socialist workers party not formed in Australia? For the same reason Socialism does not exist in the United States, the United Kingdoms, Canada, or any other Anglosphere nation. The workers have not yet established it, and the power of Capital has not fully ceded over to "contradictions".

Yet, Lenin and Marx and others were, and are, correct. Today, Socialism is discussed. There are Socialist movements. Workers feel exhausted, alienated, and angry with their living conditions. While Lenin believed in Vanguardism, the Marxist analysis he relied upon has still held up. Capitalism is now in a state of critique now that it is fully formed, and the solution of workers is Socialism. Failing that, a bourgeois guided reaction against Socialism into Fascism. Lenin wrote about this as well, in his works on Imperialism and Fascism.

I hope this lengthy response is a good enough answer for now.