But as of Monday, many users were added to a waitlist and greeted by a message that said, "Due to massive demand, we have placed you on our waitlist," the Associated Press reported.
Reuters reported that the app is like Twitter, but people can't edit their "truths" once posted.
The app, which had a "beta" launch last week, is the top free app in the U.S., according to Apple’s rankings, the AP reported.
Last week, Donald Trump Jr. tweeted a screenshot of his father's first post on the app.
"Get Ready! Your favorite president will see you soon!" it said.
Trump was banned from Twitter, Facebook, and YouTube following the January 6 riot at the U.S. Capitol last year.
This isn't Trump's first attempt at starting a social media channel.
Last May, a blog, "From the Desk of Donald Trump," was launched but was shut down in June.