thunderbolt/ usb 4 adapter

Hi, I just bought a new MacBook Air as my 2012 has died. I'm trying to set it up and got to the Migration Assistant stage; found my external hard drive to do the transfer and the new Air has no standard USB port-I stress that I am not techie AT ALL. I've tried searching online but I am bewildered.

Could someone please direct me to an adapter that I can plug my very old USB external drive into, which will then plug into the new Air. I would be so so grateful. Thank you.

Also, if I carry on or stop the set up at this stage, will it take me back to it??