"Ich würde ihn gerne anlegen."
The German could be "Ich würde den Betrag gerne anlegen" - "I would like to invest that amount." Or it could be "Ich würde den Verband gerne anlegen" - "I would like to put on the bandage" Or "Ich würde den Taucheranzug gerne anlegen" - "I would like to put on the scuba gear."
None of this matches the given translation "I would like to apply him." Neither do I understand the meaning.
I'd rather duolingo would use less pronouns for ambiguous sentences and more nouns like "Betrag" or "Verband" to make it possible to chose the right meaning.