Looking at the specification, it is a bottom end bike with tiny battery only 6 speed and rim brakes. It likely has a fairly low current controller, and that is the limit on power, so uphill performance will be poor. You can help it up by changing down to the lowest gear.
Trouble with this bike is if you upgrade to a higher current controller, you will then notice a reduction in range which may become insufficient because of the rather small battery, so then you need a bigger battery, and then you will have spent half the original price of the bike on upgrades.
I'd be tempted to treat it as a lesson learned, sell it and buy something more suitable, or for better value for money, convert a bike yourself. That is no harder than the changes you might need to make to get the Apollo doing what you want.