If you don't want to become a spender then you might want to look into the ways of doing things extremely efficiently to minimize the resources you spend as any awakened units you get now get invalidated later down the line and anything you farm now may become pointless to have later. Another game that had a similar model was Star Wars Galaxy of Heroes, which is very slow for f2p players but reasonable enough for spenders refreshing daily.

You can buy subscriptions for admin coins, subscription for eternium, refresh eternium daily many many times, buy weekly and monthly upgrade materials, and get regular sources of pulls for cheap.

That's the drive and focus of Nexon games, steering you to be a habitual spender. Luckily, there's the cash shop (seriously).

Once you blow through your early supplies you are pretty screwed when it comes to a consistent source of these things. You'll never have enough bins, quartz, eternium, contracts, or fusion cores.

The game is designed to make you super happy early on by flooding you with free characters and resources (honeymoon phase) and then hit you with the drought later when advancement slows to a pitiful crawl, especially once you get your gear sets done.

Eternium farming gear