Based on my research, the GeForce RTX 3060 Ti should be compatible with the HP Z620 Workstation, provided that your power supply unit (PSU) can support it. The two power plugs you mentioned are indeed required to connect to the power supply. If you're still unsure about which graphics card to choose...

No worries, I've been there too - writing posts too hastily and regretting it afterward. Good thing Reddit at least has a feature where you can hide posts that you're not too proud of. But I totally get it - sometimes you want to edit or unhide them. On how to unhide post on Reddit - go to your prof...