A lot of the allegations are based on foreign media, and they're not actually in dispute. Here's a "Storify" on it (series of tweets, lots of them with links to foreign press):
https://storify.com/pr01etar1at/getting-started
The basic facts are a venture that Trump's companies are a partner in have been trying to get permits to build a project in Argentina. The lead partners are part of Trump's innner circle and were with his group on election night. For months there have been delays getting the required approvals. A few days after the election, he has a call with Pres. Macri, and what do you know, the next day the Trump group announces they'll break ground in 2017!!
That much appears certain. The only thing missing is a tape recording of Trump asking Macri for this 'favor', from Pres. to Pres, you know, mutual interests, Trump and Argentina.