iMac late 2013 connect as secondary display to MacBook pro 2020
Ok so i have a late 2013 iMac that i wish to use as a secondary display for my new 2020 mac book pro. I purchase apple usb-c to Thunderbolt 2 connector and a Thunderbolt 2 cable, i have connected everything. I followed all the advice (checked that keyboard FN keys are activated) but when i hit Command+F2 ...all i get is a sound and nothing else. I have followed all advice and haven't found any possible solution as to why its not working. I rebooted each mac, i have them connected while on the same network and both open to the desktop. I have even made sure my macbook was connected on the AC adapter, i have tried every port to see if i perhaps was working with a dud ...still nothing.
Any advice because after spending 125$ on cable to attempt to achieve this i need to know if i can simply return them and give up my pursuit.
iMac 27″, macOS 10.15