The following entry requirements must be observed at the moment (22.10.2021):
Upon entry, a valid Covid-19 PCR test with negative result must be available, which is not older than 7 days upon arrival and was issued by a laboratory certified in the country of departure. The result must be in English. Also for travelers who are vaccinated against Covid-19, a negative PCR test is required upon entry.
Likewise the completed health questionnaire 1 LINK
The health questionnaire 2 LINK
And the entry form LINK
Travel and safety information - Auswärtiges Amt LINK
Make sure you have adequate travel health insurance coverage.