Hi Clara
I would recommend a concealer first, over the acne marks, and then try a foundation. You might want to try a mousse, cream or powder foundation. I won’t often recommend it because it is not my favourite type of foundation, but in this case I think it will be the most helpful in covering the marks without being oily. The thickness of the foundation will also act as a "filler" for the "grooves", whereas a liquid foundation would run over the marks and not fill them in.
Good luck!