The user does not have change authorisation for the shipping point. You need to assign authorisation object V_LIKP_VST (activity 02) to this user.
From a technical viewpoint, the error is raised here:
SAPMV50A / FORM BERECHTIGUNG_PRUEFEN
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* Berechtigung für diese Aktion in dieser Versandstelle
AUTHORITY-CHECK OBJECT 'V_LIKP_VST'
ID 'VSTEL' FIELD likp-vstel
ID 'ACTVT' FIELD bp_actvt.
* Keine Berechtigung
IF sy-subrc NE 0.
bp_subrc = sy-subrc.
IF bp_actvt NE actvt_04.
PERFORM lieferung_entsperren USING likp-vbeln.
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The authority check will fail if user does not have change authorisation for authorisation object V_LIKP_VST