Don't see MEW account balance in MetaMask extension

I’m new to the Crypto scene and have run into a problem while trying to purchase tokens.

I installed the MetaMask extension (for Firefox) but I don’t see my MEW ETH balance. I used the MEW seed phrase. The link between MEW and the extension is apparently missing.

Double-clicking the extension, there is an account with a balance of 0 ETH. The “account” is apparently an address, but it doesn’t match my MEW account address.

A thought - do I have to manually send ETH from my MEW wallet to the MetaMask wallet? That wasn’t in the instructions provided to me.

What am I missing?