Pool frustrations

I have a 6473L pool, just one of those cheapish bestway above ground (https://www.mitre10.co.nz/shop/bestway-steel-pro-swimming-pool-3-66-x-0-76m/p/323000).

I use https://www.thewarehouse.co.nz/p/splash-spa-chlorine-pills-1kg/R2097803.html and https://www.thewarehouse.co.nz/p/splash-multi-attack-chlorine-pills-1kg/R2097796.html which contain both chlorine, a sunscreen, a clarifying agent among other things.

I cannot, for the life of me, keep this fucking pool clean. It's gotten to the point where I will be refusing to put it up again next year because I'm constantly cleaning it, scrubbing it, cleaning the filter which fills with algae over one day, and everyone just moans 'Oh it's too cold, oh it's kinda green' etc.

What the hell am I doing wrong?