Looks like you didn't mix it well enough. Form the volcano, pour a little water in and mix it by working the walls of the volcano into the wet part. You add another bit of the water and work it in until you finish all the water. After that you work the mix for a few extra minutes working it through the full depth, repeat mixing and stabbing with your shovel or trowel. When you think you are done you still lift the mix from the bottom. And fold it upon itself to make sure you didn't leave some dry mix under all. And you mix and stab the mix some more for another 10 minutes.

When you place the mix you have to tamp it in and vibrate it. Make all the bubbles come out allow the gravel to settle into the hole. Them, without overdoing the vibration, the cement sand grout will rise and that is what you float smooth.

As to repairs, if it has set then wirebrush clean while the concrete is weak to expose the agregate. Then you can try a mortar patch. Ideally as thick as possible and with no thin feathered edges as those will just spall as it dries. Close to vertical edges to the patches you are putting in. Hopefully there's something else over the floor to protect it and reduce the risk of the repair popping out.

Mist with water while curing per the instructions. Drying out too much leads to cracking from shrinkage.