@Weitentaaal:
If you have multiple or previous installations of free pascal then Lazarus might pick up on the wrong version.
To investigate, see this post (literal issue of TS there is different but cause is the same).
PS: Are you sure you started the right lazarus version that fpcupdeluxe just installed ?
i tried to solve it like suggested in the Post you mentioned, but without success. So i decided do completly remove Lazarus and install both versions i need. I follewed this Tutorial:
https://wiki.freepascal.org/Multiple_Lazarus, and it did work. The first time i was following the same example, but i messed up somewhere i guess.
im not sure where the error was but i got it to run now.
Thank you guys once again for your help.