Connect an iPad Pro to an older Macbook Pro using a generic USB-C to USB-A cable The older Macbook Pro I'm using doesn't have USB-C ports. The cable that came with the iPad Pro I'm using came with a USB-C to USB-C cable. I tried to use a USB-C to USB-A cable from a Huawei phone to connect the iPad and the Macbook, but there was no connection whatsoever.

Does it mean I'll have to get hold of a very specific USB-C to USB-A cable, such as a “Belkin USB-A to USB-C Cable (USB 3.1)” (cf. https://support.apple.com/en-us/HT209186#computer)?
No, there's no need to use that specific cable. Any standards-compliant USB-C to USB-A cable should work.