The verb schaffen

The verb schaffen has various meanings in different contexts.

Like “to achieve”, to have achieved a goal.

Markus hat die Prüfung bestanden. Er hat es endlich geschafft

Markus has finally passed the exam, at last he has succeeded

in fixed structures:

Die Kälte macht ihm zu schaffen
the cold is killing him
Markus ist total geschafft
Markus is totally exhausted

The verb erreichen:

as in “to locate”:

Sie können uns nach 20 Uhr unter dieser Nummer erreichen
You can reach us after 20 o’clock at this number

as “get” . In contrast to the verb schaffen, erreichen is rather used in contexts where the goal has not yet been achieved:

Wenn du etwas erreichen willst, musst du hart arbeiten.
If you want to achieve something, you have to work hard