The 26-year-old Scot completed his move to the Tigers on Monday in a club record fee for an outgoing Canaries player, reportedly exceeding £6m.
"We didn't have to sell anyone but the finances involved were strongly in our favour," Adams told BBC Radio Norfolk.
"Robert was an excellent player. But the finances were a big factor."
He added: "I wish him all the best. Some players will chase moves, but Robert wasn't like that."
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