Nynäshamn motorway entrance and exit

I got failed for the sixth time in Farsta.

I failed because I merged into to Nynäshamn motorway late.

It is weird motorway, when you enter the highway at some place you have not to change lane and some places you have to merge into motorway. But you have to do that as early as possible. You need to know all entrance and exit completely, otherwise you get failed

Thare two alternatives.

Towards Nynäshamn: Own lane

Towards Stockholm: On-ramp and then change due to oncoming bus lane.

At the end, examiner told me when you enter a highway you have to look at the line,
If it is thick you have to immediately change lane otherwise you are obligated to stay at the lane.

She pointed out the thing I have not seen in the theory book