This machine is operated manually.
Please switch to manual mode.
You open this door manually.
It broke down, so we switched from automatic to manual.
I set the camera to manual mode and took the photo.
automatic; auto- · intransitive verb
手動 means 'manual' (operated by hand), the direct opposite of オートマチック 'automatic' for machines and devices.
手動 means 'manually operated', the direct opposite of 電動 'electrically powered'.
自動的 describes something happening without human intervention, while 手動 describes something operated manually by hand.
Compound of 手 (hand) and 動 (move), literally 'hand-move'. The exact historical derivation is uncertain, but the meaning is transparent from the kanji.