The campaign had a license to play Abba's music through our agreement with BMI and ASCAP, says a spokesperson to the news agency AP.
It was Svenska Dagbladet that noticed the incident after the newspaper was present at an election rally in Minnesota and observed that Trump supporters were entertained with Abba's music.
"Our record company Universal will take care of it," wrote Björn Ulvaeus to TT about the matter.
According to Universal, "no permission or license was given to Trump," the company told SvD.
But the copyright organization BMI now partially agrees with Trump, writes SvD.
The organization explains to the newspaper that Trump's campaign has a so-called "political license," which gives access to over 22 million licensed songs, including Abba's.
At the same time, artists or songwriters have the opportunity to protest and stop politicians from using their songs.
During the election rally, music videos with Abba were also shown, but it is not clear whether they had the additional licenses required to display video material in political contexts.
Artists demanding that Trump stop using their music at his election rallies has been a recurring theme throughout his political career. The Rolling Stones, Foo Fighters, Céline Dion, Bruce Springsteen, Rihanna, and Neil Young are some of those who have previously protested.