As of right now, there is no way to directly purchase FTT on Coinbase. However, there are a few indirect ways that you can do so.
One way is to first purchase Ethereum or Bitcoin on Coinbase and then use a cryptocurrency exchange that supports FTT to convert your ETH/BTC into FTT. Another way is to use a decentralized exchange like Uniswap, where you can trade ETH/FTT directly.
NOTE: Warning: Coinbase does not currently support the purchase of FTT tokens (Fetch.AI). Coinbase is a digital currency exchange and does not provide support for any other type of asset or token. If you are interested in buying FTT tokens, please explore other options that may be available to you.
The most popular and easiest way to buy FTT is through the FTX cryptocurrency exchange. FTX supports spot and derivative trading for a variety of digital assets, including FTT.
To get started, create an account on FTX and deposit ETH or BTC into your account. Once your deposit has been processed, you can then convert your ETH or BTC into FTT.