Folkertsma made her league debut against Utrecht on 30 November 2012.[3] She scored her first league goal against VV Alkmaar on 22 March 2013, scoring in the 90th+3rd minute.[4]
PSV
Folkertsma made her league debut against PEC Zwolle on 21 August 2015.[5] She scored her first league goal against ADO Den Haag on 28 August 2015, scoring in the 11th minute.[6] Folkerstma scored a hattrick against Alkmaar on 16 October 2015.[7]
Ajax
On 16 June 2017, Folkertsma was announced at Ajax.[8] She made her league debut against Achilles '29 on 3 September 2017.[9] Folkertsma scored her first league goal against ADO Den Haag on 15 December 2017, scoring in the 20th minute.[10]
Twente
Folkertsma made her league debut against PSV on 7 September 2018.[11] She scored her first league goal against PEC Zwolle on 14 September 2018, scoring in the 36th minute.[12] On 16 April 2019, it was announced that her contract had been extended.[13]
Bordeaux
In June 2021, while she was preparing for the 2020 Olympics it was revealed Folkertsma had agreed contract terms with French club Bordeaux.[14] She made her league debut against Saint-Étienne on 28 August 2021.[15] Folkertsma scored her first league goal against Soyaux on 4 September 2021, scoring in the 2nd minute.[16]
Feyenoord
In May 2023, Dutch club Feyenoord announced that it had reached a deal with Folkertsma for her to join the club from the start of the upcoming season.[17] She made her league debut against Twente on 1 October 2023.[18] She will share captain duties with Jacintha Weimar and Esmee de Graaf from the 2024-25 season.[19]