Your indentation is wrong - the if..elif..else statements should be aligned, like:

doorgaan = True
teRadenGetal=6
while (doorgaan):
  invoer= input('Kies een getal')
  if getal < teRadenGetal:
    doorgaan=true
    print('Lager')
  elif (getal > teRadenGetal):
    doorgaan=true
    print('Hoger')
  else:
    print('Correct')

(Also, you had a ) that shouldn't have been there on line 8. i have removed that above).
Please upvote if this helps :)

Thanks guys for helping me out :)

Everytime, I try to run it it I get:

Traceback (most recent call last):
File "python", line 8
elif (getal > teRadenGetal)):
^
SyntaxError: invalid syntax

I don't know how to fix it. I hope someone can help me