Hello Benjamin Noack ,
When using the MCUXpresso Config tool to config peripherals, it generate two files "peripherals.c" and "peripherals.h",
it only includes the initialize information code, the drivers are in driver files, when you create project, you need choose
peripherals driver that you need. Please ignore the error , in fact, the initialize code has generate in the peripherals .c file,
just export them , then add them into your project 。

Also if you need MCUXpresso IDE, you can refer to Marek's said righting click the error
reminder, then choose Add component .
Hope it helps,
Alice