If you don't want to use batteries, you can buy one of the following two power supplies to power the gate opener:
https://topens.com/products/ups01-uninterrupted-power-supply-adapter-100-240vac-to-24vdc-150w-transformer-for-automatic-gate-openers (compatible with AC, batteries and solar panels)
https://topens.com/products/dps180-u-waterproof-100-240vac-to-24vdc-power-supply-transformer-for-automatic-gate-openers (can only use AC, not compatible with batteries)
By vevor