In the Axon app you have the easy option of buying & selling your crypto tokens through a connected bank account of yours.
In order for you to be able to connect a bank account, you need to have successfully passed KYC Verification first.
How to connect my bank account?
After successfully passing the KYC Verification, go to the Wallets section of you app
Below your portfolio graph, tap on the Add Wallet button
Select Fiat Wallet
Follow the on-screen instructions of how to connect an account according to your region and bank