No ground bus in panel
All the wiring is in THHN wires inside metal conduit.  Since the metal conduit carries the ground, there's no need for any ground wires, therefore no need for any ground bus.
&quot;That was easy...&quot;
Note that nobody puts in metal conduit for their health.  They use metal conduit because the municipality requires it.  So if you are DIYing electrical and got all your knowledge off Youtube or books at the store, you may have used the popular Romex/NM cable. If so, you'll have to contact your local inspector's office and ask them what is required, and upgrade to that if called for.
It can be frustrating to have to learn a second method after learning a first one and doing the work... but really, conduit is a much better setup and much more maintainable and easy to change/upgrade.  Once you get the hang of it, you'll be smug about using conduit :)

Note that several of the circuits in your panel are sharing a neutral.  (twice as many hots as neutrals in some pipes).  The breakers on the 2 hots need to have a &quot;handle tie&quot; between them, or, use a 2-pole 240V breaker of that same amperage.

If you really need a ground bar, then the manufacturer's label will specify certain accessory ground bar models which are designed to bolt right into the holes pre-drilled in the panel.