I'm trying to play around with the DyDx Protocol on Ropsten, but to get any further I need to have some USDC in my account. I've had no luck googling for this. There seems to be this website for it, but it doesn't do anything, it just says ur USDC will arrive shortly but nothing happens after. The token contract is this, and I can see that there have been some transactions, but I don't know how I can exactly get some.
A dYdX API endpoint can be used to request testnet tokens.
Refer to the documentation for more details.
Try Uniswap protocol. Go to the https://app.uniswap.org/#/swap (you'll need metamask or similar tool). The idea behind this is that you swap ETH for some other token. You can specify the contract address to define which token you need. I just did this for USDC in the Kovan testnet.
Now that Ropsten's deprecated (along with every other Ethereum testnet besides Goerli), make sure to get Goerli testETH from a reliable faucet (like https://goerlifaucet.com). Uniswap is a good option to switch between tokens.