40 Grk “going down.” The participle καταβάς (katabas) has been translated as a finite verb due to requirements of contemporary English style.
41 ἐπιπίπτω 1.b has “ἐπέπεσεν αὐτῷ he threw himself upon him Ac 20:10.”
42 Grk “on him”; the referent (the young man) has been specified in the translation for clarity.
43 συμπεριλαμβάνω has “to throw one’s arms around, embrace to be supplied Ac 20:10.” However, “embraced the young man” might be taken (out of context) to have erotic implications, while “threw his arms around him” would be somewhat redundant since “threw” has been used in the previous phrase.
44 Grk “for his life is in him” (an idiom).

In other versions

But Paul went down and bent over him, and taking him in his arms, said, “Do not be alarmed, for his life is in him.”

Paul went down, threw himself on the young man and put his arms around him. “Don’t be alarmed,” he said. “He’s alive!”

But Paul went down, bent over him, embraced him, and said, “Don’t be alarmed, because he’s alive.”

Paul went down, bent over him, and took him into his arms. “Don’t worry,” he said, “he’s alive!”

But Paul went down and threw himself on him, and putting his arms around him, said, “Do not be distressed, for his life is in him.”

And Paul went down, and fell on him, and embracing him said, Trouble not yourselves; for his life is in him.

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