vollständig
complete
Having all necessary or associated parts; with nothing missing; complete.
Bitte stellen Sie sicher, dass Ihre Bewerbungsunterlagen vollständig sind.
Please make sure that your application documents are complete.

complete
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complete
Having all necessary or associated parts; with nothing missing; complete.
Bitte stellen Sie sicher, dass Ihre Bewerbungsunterlagen vollständig sind.
Please make sure that your application documents are complete.

The word is made up of 'voll' (full) and 'ständig' (derived from 'Stand', standing/state). It describes a state that is 'full', meaning that nothing is missing.
Nach dem Umzug war das Chaos groß, aber jetzt ist die Wohnung wieder vollständig eingerichtet.
After the move, the chaos was huge, but now the apartment is fully furnished again.
The meaning depends on the word's function in the sentence. If 'vollständig' (complete) stands before a noun, it means 'complete' (all parts are there). If it modifies a verb or adjective, it means 'entirely' or 'totally'.
Die Liste der Teilnehmer ist noch nicht vollständig.
The list of participants is not yet complete.
When it is about nothing being missing, 'vollständig' (complete) is often used with information or collections. Typical examples are: 'vollständige Unterlagen' (complete documents), 'vollständiger Name' (full name), or 'eine vollständige Adresse' (a complete address).
Für die Anmeldung benötigen wir Ihren vollständigen Namen.
For registration, we need your full name.
As an adverb meaning 'entirely', 'vollständig' (completely) often describes the completion of a process. Common verbs are: 'vollständig genesen' (to recover completely), 'vollständig zerstören' (to destroy completely), or 'ein Formular vollständig ausfüllen' (to fill out a form completely).
Das alte Gebäude wurde bei dem Feuer vollständig zerstört.
The old building was completely destroyed in the fire.
all
'all' and 'vollständig' both have to do with completeness. 'all' is used when you mean the whole quantity: all people, all things, or everything together. 'vollständig' is more about saying that nothing is missing or that something is fully completed. It fits especially with lists, documents, information, or work. You can say: 'Alle Seiten sind da' (All the pages are there), but 'Der Bericht ist vollständig' (The report is complete) sounds more natural when the question is whether anything is still missing.

Wegen der Arbeit schickte der Fahrer die Unterlagen erst am Abend vollständig ab.
Because of work, the driver did not send off the complete documents until the evening.
Ali bringt morgen alle Sportsachen zum Training mit.
Ali is bringing all his sports gear to training tomorrow.